diff --git a/app/models/api_secret.rb b/app/models/api_secret.rb
index d7bb85703..5c2703da0 100644
--- a/app/models/api_secret.rb
+++ b/app/models/api_secret.rb
@@ -14,6 +14,6 @@ class ApiSecret < ApplicationRecord
   def user_api_secret_count
     return if user && user.api_secrets.count < 20
 
-    errors.add(:user, "API secret limit of 20 per user has been reached")
+    errors.add(:user, I18n.t("models.api_secret.api_limit_reached"))
   end
 end
diff --git a/app/models/application_record.rb b/app/models/application_record.rb
index 8dd6494d9..66ce77a4b 100644
--- a/app/models/application_record.rb
+++ b/app/models/application_record.rb
@@ -60,7 +60,8 @@ class ApplicationRecord < ActiveRecord::Base
 
     return superclass.decorator_class(called_on) if superclass.respond_to?(:decorator_class)
 
-    raise UninferrableDecoratorError, "Could not infer a decorator for #{called_on.class.name}."
+    raise UninferrableDecoratorError,
+          I18n.t("models.application_record.uninferrable", class: called_on.class.name)
   end
 
   def self.statement_timeout
diff --git a/app/models/article.rb b/app/models/article.rb
index 973d51b59..998e1d0a5 100644
--- a/app/models/article.rb
+++ b/app/models/article.rb
@@ -29,10 +29,12 @@ class Article < ApplicationRecord
 
   # The date that we began limiting the number of user mentions in an article.
   MAX_USER_MENTION_LIVE_AT = Time.utc(2021, 4, 7).freeze
-  UNIQUE_URL_ERROR = "has already been taken. " \
-                     "Email #{ForemInstance.email} for further details.".freeze
   PROHIBITED_UNICODE_CHARACTERS_REGEX = /[\u202a-\u202e]/ # BIDI embedding controls
 
+  def self.unique_url_error
+    I18n.t("models.article.unique_url", email: ForemInstance.email)
+  end
+
   has_one :discussion_lock, dependent: :delete
 
   has_many :mentions, as: :mentionable, inverse_of: :mentionable, dependent: :delete_all
@@ -58,17 +60,20 @@ class Article < ApplicationRecord
            inverse_of: :commentable,
            class_name: "Comment"
 
-  validates :body_markdown, bytesize: { maximum: 800.kilobytes, too_long: "is too long." }
+  validates :body_markdown, bytesize: {
+    maximum: 800.kilobytes,
+    too_long: proc { I18n.t("models.article.is_too_long") }
+  }
   validates :body_markdown, length: { minimum: 0, allow_nil: false }
   validates :body_markdown, uniqueness: { scope: %i[user_id title] }
   validates :cached_tag_list, length: { maximum: 126 }
   validates :canonical_url,
-            uniqueness: { allow_nil: true, scope: :published, message: UNIQUE_URL_ERROR },
+            uniqueness: { allow_nil: true, scope: :published, message: unique_url_error },
             if: :published?
   validates :canonical_url, url: { allow_blank: true, no_local: true, schemes: %w[https http] }
   validates :comments_count, presence: true
   validates :feed_source_url,
-            uniqueness: { allow_nil: true, scope: :published, message: UNIQUE_URL_ERROR },
+            uniqueness: { allow_nil: true, scope: :published, message: unique_url_error },
             if: :published?
   validates :feed_source_url, url: { allow_blank: true, no_local: true, schemes: %w[https http] }
   validates :main_image, url: { allow_blank: true, schemes: %w[https http] }
@@ -379,7 +384,7 @@ class Article < ApplicationRecord
         .tr("\n", " ")
         .strip
     else
-      "A post by #{user.name}"
+      I18n.t("models.article.a_post_by", user_name: user.name)
     end
   end
 
@@ -434,18 +439,20 @@ class Article < ApplicationRecord
     return unless edited?
 
     if edited_at.year == Time.current.year
-      edited_at.strftime("%b %e")
+      I18n.l(edited_at, format: :short)
     else
-      edited_at.strftime("%b %e '%y")
+      I18n.l(edited_at, format: :short_with_yy)
     end
   end
 
   def readable_publish_date
     relevant_date = displayable_published_at
-    if relevant_date && relevant_date.year == Time.current.year
-      relevant_date&.strftime("%b %-e")
-    else
-      relevant_date&.strftime("%b %-e '%y")
+    return unless relevant_date
+
+    if relevant_date.year == Time.current.year
+      I18n.l(relevant_date, format: :short)
+    elsif relevant_date
+      I18n.l(relevant_date, format: :short_with_yy)
     end
   end
 
@@ -606,7 +613,7 @@ class Article < ApplicationRecord
   end
 
   def update_notifications
-    Notification.update_notifications(self, "Published")
+    Notification.update_notifications(self, I18n.t("models.article.published"))
   end
 
   def update_notification_subscriptions
@@ -664,7 +671,7 @@ class Article < ApplicationRecord
     add_tag_adjustments_to_tag_list
 
     # check there are not too many tags
-    return errors.add(:tag_list, "exceed the maximum of 4 tags") if tag_list.size > 4
+    return errors.add(:tag_list, I18n.t("models.article.too_many_tags")) if tag_list.size > 4
 
     # check tags names aren't too long and don't contain non alphabet characters
     tag_list.each do |tag|
@@ -691,48 +698,48 @@ class Article < ApplicationRecord
   def validate_video
     if published && video_state == "PROGRESSING"
       return errors.add(:published,
-                        "cannot be set to true if video is still processing")
+                        I18n.t("models.article.video_processing"))
     end
 
     return unless video.present? && user.created_at > 2.weeks.ago
 
-    errors.add(:video, "cannot be added by member without permission")
+    errors.add(:video, I18n.t("models.article.video_unpermitted"))
   end
 
   def validate_collection_permission
     return unless collection && collection.user_id != user_id
 
-    errors.add(:collection_id, "must be one you have permission to post to")
+    errors.add(:collection_id, I18n.t("models.article.series_unpermitted"))
   end
 
   def validate_co_authors
     return if co_author_ids.exclude?(user_id)
 
-    errors.add(:co_author_ids, "must not be the same user as the author")
+    errors.add(:co_author_ids, I18n.t("models.article.same_author"))
   end
 
   def validate_co_authors_must_not_be_the_same
     return if co_author_ids.uniq.count == co_author_ids.count
 
-    errors.add(:base, "co-author IDs must be unique")
+    errors.add(:base, I18n.t("models.article.unique_coauthor"))
   end
 
   def validate_co_authors_exist
     return if User.where(id: co_author_ids).count == co_author_ids.count
 
-    errors.add(:co_author_ids, "must be valid user IDs")
+    errors.add(:co_author_ids, I18n.t("models.article.invalid_coauthor"))
   end
 
   def past_or_present_date
     return unless published_at && published_at > Time.current
 
-    errors.add(:date_time, "must be entered in DD/MM/YYYY format with current or past date")
+    errors.add(:date_time, I18n.t("models.article.invalid_date"))
   end
 
   def canonical_url_must_not_have_spaces
     return unless canonical_url.to_s.match?(/[[:space:]]/)
 
-    errors.add(:canonical_url, "must not have spaces")
+    errors.add(:canonical_url, I18n.t("models.article.must_not_have_spaces"))
   end
 
   def user_mentions_in_markdown
@@ -742,7 +749,8 @@ class Article < ApplicationRecord
     mentions_count = Nokogiri::HTML(processed_html).css(".mentioned-user").size
     return if mentions_count <= Settings::RateLimit.mention_creation
 
-    errors.add(:base, "You cannot mention more than #{Settings::RateLimit.mention_creation} users in a post!")
+    errors.add(:base,
+               I18n.t("models.article.mention_too_many", count: Settings::RateLimit.mention_creation))
   end
 
   def create_slug
diff --git a/app/models/broadcast.rb b/app/models/broadcast.rb
index 6f5485e33..b017d1b2f 100644
--- a/app/models/broadcast.rb
+++ b/app/models/broadcast.rb
@@ -32,7 +32,7 @@ class Broadcast < ApplicationRecord
       type_of == "Announcement" &&
       [nil, id].exclude?(first_broadcast.pick(:id))
 
-    errors.add(:base, "You can only have one active announcement broadcast")
+    errors.add(:base, I18n.t("models.broadcast.single_active"))
   end
 
   def update_active_status_updated_at
diff --git a/app/models/comment.rb b/app/models/comment.rb
index 6b9e46418..f72dcfbb5 100644
--- a/app/models/comment.rb
+++ b/app/models/comment.rb
@@ -9,9 +9,6 @@ class Comment < ApplicationRecord
 
   COMMENTABLE_TYPES = %w[Article PodcastEpisode].freeze
 
-  TITLE_DELETED = "[deleted]".freeze
-  TITLE_HIDDEN = "[hidden by post author]".freeze
-
   URI_REGEXP = %r{
     \A
     (?:https?://)?  # optional scheme
@@ -59,7 +56,8 @@ class Comment < ApplicationRecord
   validates :reactions_count, presence: true
   validates :commentable, on: :create, presence: {
     message: lambda do |object, _data|
-      "#{object.commentable_type.presence || 'item'} has been deleted."
+      I18n.t("models.comment.has_been_deleted",
+             type: I18n.t("models.comment.type.#{object.commentable_type.presence || 'item'}"))
     end
   }
 
@@ -97,6 +95,14 @@ class Comment < ApplicationRecord
       .to_h
   end
 
+  def self.title_deleted
+    I18n.t("models.comment.deleted")
+  end
+
+  def self.title_hidden
+    I18n.t("models.comment.hidden")
+  end
+
   def search_id
     "comment_#{id}"
   end
@@ -134,8 +140,8 @@ class Comment < ApplicationRecord
   end
 
   def title(length = 80)
-    return TITLE_DELETED if deleted
-    return TITLE_HIDDEN if hidden_by_commentable_user
+    return self.class.title_deleted if deleted
+    return self.class.title_hidden if hidden_by_commentable_user
 
     text = ActionController::Base.helpers.strip_tags(processed_html).strip
     truncated_text = ActionController::Base.helpers.truncate(text, length: length).gsub("&#39;", "'").gsub("&amp;", "&")
@@ -148,9 +154,9 @@ class Comment < ApplicationRecord
 
   def readable_publish_date
     if created_at.year == Time.current.year
-      created_at.strftime("%b %-e")
+      I18n.l(created_at, format: :short)
     else
-      created_at.strftime("%b %-e '%y")
+      I18n.l(created_at, format: :short_with_yy)
     end
   end
 
@@ -315,11 +321,13 @@ class Comment < ApplicationRecord
   def discussion_not_locked
     return unless commentable_type == "Article" && commentable.discussion_lock
 
-    errors.add(:commentable_id, "the discussion is locked on this Post")
+    errors.add(:commentable_id, I18n.t("models.comment.locked"))
   end
 
   def published_article
-    errors.add(:commentable_id, "is not valid.") if commentable_type == "Article" && !commentable.published
+    return unless commentable_type == "Article" && !commentable.published
+
+    errors.add(:commentable_id, I18n.t("models.comment.is_not_valid"))
   end
 
   def user_mentions_in_markdown
@@ -329,7 +337,9 @@ class Comment < ApplicationRecord
     mentions_count = Nokogiri::HTML(processed_html).css(".mentioned-user").size
     return if mentions_count <= Settings::RateLimit.mention_creation
 
-    errors.add(:base, "You cannot mention more than #{Settings::RateLimit.mention_creation} users in a comment!")
+    errors.add(:base,
+               I18n.t("models.comment.mention_too_many",
+                      count: Settings::RateLimit.mention_creation))
   end
 
   def record_field_test_event
diff --git a/app/models/feedback_message.rb b/app/models/feedback_message.rb
index bd2261ab3..7a0c00d44 100644
--- a/app/models/feedback_message.rb
+++ b/app/models/feedback_message.rb
@@ -9,10 +9,13 @@ class FeedbackMessage < ApplicationRecord
   has_many :notes, as: :noteable, inverse_of: :noteable, dependent: :destroy
 
   REPORTER_UNIQUENESS_SCOPE = %i[reported_url feedback_type].freeze
-  REPORTER_UNIQUENESS_MSG = "(you) previously reported this URL.".freeze
   CATEGORIES = ["spam", "other", "rude or vulgar", "harassment", "bug", "listings"].freeze
   STATUSES = %w[Open Invalid Resolved].freeze
 
+  def self.reporter_uniqueness_msg
+    I18n.t("models.feedback_message.reported")
+  end
+
   scope :open_abuse_reports, -> { where(status: "Open", feedback_type: "abuse-reports") }
   scope :all_user_reports, lambda { |user|
     user.reporter_feedback_messages
@@ -31,7 +34,7 @@ class FeedbackMessage < ApplicationRecord
             inclusion: {
               in: STATUSES
             }
-  validates :reporter_id, uniqueness: { scope: REPORTER_UNIQUENESS_SCOPE, message: REPORTER_UNIQUENESS_MSG },
+  validates :reporter_id, uniqueness: { scope: REPORTER_UNIQUENESS_SCOPE, message: reporter_uniqueness_msg },
                           if: :abuse_report? && :reporter_id
 
   def abuse_report?
diff --git a/app/models/github_issue.rb b/app/models/github_issue.rb
index a5c1c5b05..a923eded6 100644
--- a/app/models/github_issue.rb
+++ b/app/models/github_issue.rb
@@ -72,10 +72,10 @@ class GithubIssue < ApplicationRecord
     def error_message(url)
       if PATH_COMMENT_REGEXP.match?(url)
         _, issue_id = comment_repo_and_issue_id(url)
-        "Issue comment #{issue_id} not found"
+        I18n.t("models.github_issue.issue_comment_not_found", issue_id: issue_id)
       else
         _, issue_id = issue_or_pull_repo_and_issue_id(url)
-        "Issue #{issue_id} not found"
+        I18n.t("models.github_issue.issue_not_found", issue_id: issue_id)
       end
     end
   end
diff --git a/app/models/html_variant.rb b/app/models/html_variant.rb
index 35c5a3efb..95b450915 100644
--- a/app/models/html_variant.rb
+++ b/app/models/html_variant.rb
@@ -56,7 +56,7 @@ class HtmlVariant < ApplicationRecord
     return if group == "campaign"
 
     published_and_approved = (approved && (html_changed? || name_changed? || group_changed?)) && persisted?
-    errors.add(:base, "cannot change once published and approved") if published_and_approved
+    errors.add(:base, I18n.t("models.html_variant.no_edits")) if published_and_approved
   end
 
   def prefix_all_images
diff --git a/app/models/identity.rb b/app/models/identity.rb
index 055aea7db..80572ad3e 100644
--- a/app/models/identity.rb
+++ b/app/models/identity.rb
@@ -2,9 +2,6 @@
 #        :delete for the relationship.  That means no before/after
 #        destroy callbacks will be called on this object.
 class Identity < ApplicationRecord
-  NO_EMAIL_MSG = "No email found. Please relink your %<provider>s " \
-                 "account to avoid errors.".freeze
-
   belongs_to :user
 
   scope :enabled, -> { where(provider: Authentication::Providers.enabled) }
@@ -44,6 +41,6 @@ class Identity < ApplicationRecord
   end
 
   def email
-    auth_data_dump&.info&.email || format(NO_EMAIL_MSG, provider: provider)
+    auth_data_dump&.info&.email || I18n.t("models.identity.no_email_msg", provider: provider)
   end
 end
diff --git a/app/models/listing.rb b/app/models/listing.rb
index 971188dd0..c84e7e014 100644
--- a/app/models/listing.rb
+++ b/app/models/listing.rb
@@ -115,15 +115,14 @@ class Listing < ApplicationRecord
   def restrict_markdown_input
     markdown_string = body_markdown.to_s
     if markdown_string.scan(/(?=\n)/).count > 12
-      errors.add(:body_markdown,
-                 "has too many linebreaks. No more than 12 allowed.")
+      errors.add(:body_markdown, I18n.t("models.listing.too_many_linebreaks"))
     end
-    errors.add(:body_markdown, "is not allowed to include images.") if markdown_string.include?("![")
-    errors.add(:body_markdown, "is not allowed to include liquid tags.") if markdown_string.include?("{% ")
+    errors.add(:body_markdown, I18n.t("models.listing.image_not_allowed")) if markdown_string.include?("![")
+    errors.add(:body_markdown, I18n.t("models.listing.liquid_not_allowed")) if markdown_string.include?("{% ")
   end
 
   def validate_tags
-    errors.add(:tag_list, "exceed the maximum of 8 tags") if tag_list.length > 8
+    errors.add(:tag_list, I18n.t("models.listing.too_many_tags")) if tag_list.length > 8
   end
 
   def create_slug
diff --git a/app/models/mention.rb b/app/models/mention.rb
index 08813eae2..7890ee981 100644
--- a/app/models/mention.rb
+++ b/app/models/mention.rb
@@ -29,6 +29,6 @@ class Mention < ApplicationRecord
   end
 
   def permission
-    errors.add(:mentionable_id, "is not valid.") unless mentionable&.valid?
+    errors.add(:mentionable_id, I18n.t("models.mention.is_not_valid")) unless mentionable&.valid?
   end
 end
diff --git a/app/models/navigation_link.rb b/app/models/navigation_link.rb
index b12c5f05e..445526731 100644
--- a/app/models/navigation_link.rb
+++ b/app/models/navigation_link.rb
@@ -42,7 +42,7 @@ class NavigationLink < ApplicationRecord
   # @see NavigationLink.create_or_update_by_identity
   # @see NavigationLink#strip_local_hostname
   def self.normalize_url(url)
-    parsed_url = URI.parse(url)
+    parsed_url = Addressable::URI.parse(url)
     return url unless url.match?(/^#{URL.url}/i)
 
     parsed_url.path
@@ -53,10 +53,10 @@ class NavigationLink < ApplicationRecord
   # We want to allow relative URLs (e.g. /contact) for navigation links while
   # still going through the normal validation process.
   def allow_relative_url
-    parsed_url = URI.parse(url)
+    parsed_url = Addressable::URI.parse(url)
     return unless parsed_url.relative? && url.starts_with?("/")
 
-    self.url = URI.parse(URL.url).merge(parsed_url).to_s
+    self.url = Addressable::URI.parse(URL.url).join(parsed_url).to_s
   end
 
   # When persisting to the database we store local links as relative URLs which
diff --git a/app/models/organization.rb b/app/models/organization.rb
index a77a3b169..ca4895632 100644
--- a/app/models/organization.rb
+++ b/app/models/organization.rb
@@ -6,10 +6,6 @@ class Organization < ApplicationRecord
   COLOR_HEX_REGEXP = /\A#([A-Fa-f0-9]{6}|[A-Fa-f0-9]{3})\z/
   INTEGER_REGEXP = /\A\d+\z/
   SLUG_REGEXP = /\A[a-zA-Z0-9\-_]+\z/
-  MESSAGES = {
-    integer_only: "Integer only. No sign allowed.",
-    reserved_word: "%<value>s is a reserved word. Contact site admins for help registering your organization."
-  }.freeze
 
   acts_as_followable
 
@@ -44,7 +40,7 @@ class Organization < ApplicationRecord
 
   validates :articles_count, presence: true
   validates :bg_color_hex, format: COLOR_HEX_REGEXP, allow_blank: true
-  validates :company_size, format: { with: INTEGER_REGEXP, message: MESSAGES[:integer_only], allow_blank: true }
+  validates :company_size, format: { with: INTEGER_REGEXP, message: :integer_only, allow_blank: true }
   validates :company_size, length: { maximum: 7 }, allow_nil: true
   validates :credits_count, presence: true
   validates :cta_body_markdown, length: { maximum: 256 }
@@ -57,7 +53,7 @@ class Organization < ApplicationRecord
   validates :proof, length: { maximum: 1500 }
   validates :secret, length: { is: 100 }, allow_nil: true
   validates :secret, uniqueness: true
-  validates :slug, exclusion: { in: ReservedWords.all, message: MESSAGES[:reserved_word] }
+  validates :slug, exclusion: { in: ReservedWords.all, message: :reserved_word }
   validates :slug, format: { with: SLUG_REGEXP }, length: { in: 2..18 }
   validates :slug, presence: true, uniqueness: { case_sensitive: false }
   validates :spent_credits_count, presence: true
@@ -80,6 +76,14 @@ class Organization < ApplicationRecord
   alias_attribute :old_old_username, :old_old_slug
   alias_attribute :website_url, :url
 
+  def self.integer_only
+    I18n.t("models.organization.integer_only")
+  end
+
+  def self.reserved_word
+    I18n.t("models.organization.reserved_word")
+  end
+
   def check_for_slug_change
     return unless slug_changed?
 
diff --git a/app/models/page.rb b/app/models/page.rb
index 8ada58bda..9289f8fd3 100644
--- a/app/models/page.rb
+++ b/app/models/page.rb
@@ -75,7 +75,7 @@ class Page < ApplicationRecord
   def body_present
     return unless body_markdown.blank? && body_html.blank? && body_json.blank?
 
-    errors.add(:body_markdown, "must exist if body_html or body_json doesn't exist.")
+    errors.add(:body_markdown, I18n.t("models.page.body_must_exist"))
   end
 
   # As there can only be one global landing page, we want to ensure that
diff --git a/app/models/podcast.rb b/app/models/podcast.rb
index 273731c69..65d04389d 100644
--- a/app/models/podcast.rb
+++ b/app/models/podcast.rb
@@ -21,7 +21,7 @@ class Podcast < ApplicationRecord
             presence: true,
             uniqueness: true,
             format: { with: /\A[a-zA-Z0-9\-_]+\Z/ },
-            exclusion: { in: ReservedWords.all, message: "slug is reserved" }
+            exclusion: { in: ReservedWords.all, message: I18n.t("models.podcast.slug_is_reserved") }
 
   validates :slug, unique_cross_model_slug: true, if: :slug_changed?
 
diff --git a/app/models/podcast_episode_appearance.rb b/app/models/podcast_episode_appearance.rb
index 7c4d6f5ac..09e63b03f 100644
--- a/app/models/podcast_episode_appearance.rb
+++ b/app/models/podcast_episode_appearance.rb
@@ -6,5 +6,7 @@ class PodcastEpisodeAppearance < ApplicationRecord
   belongs_to :podcast_episode
   validates :podcast_episode_id, uniqueness: { scope: :user_id }
   validates :role, presence: true
-  validates :role, inclusion: { in: %w[host guest], message: "provided role is not valid" }
+  validates :role,
+            inclusion: { in: %w[host guest],
+                         message: I18n.t("models.podcast_episode_appearance.provided_role_is_not_valid") }
 end
diff --git a/app/models/poll_skip.rb b/app/models/poll_skip.rb
index 0068c7355..7a65121c6 100644
--- a/app/models/poll_skip.rb
+++ b/app/models/poll_skip.rb
@@ -17,6 +17,6 @@ class PollSkip < ApplicationRecord
     return false unless poll
     return false unless poll.vote_previously_recorded_for?(user_id: user_id)
 
-    errors.add(:base, "cannot vote more than once in one poll")
+    errors.add(:base, I18n.t("models.poll_skip.cannot_vote_more_than_once"))
   end
 end
diff --git a/app/models/poll_vote.rb b/app/models/poll_vote.rb
index 58ad0a1da..2c145e21c 100644
--- a/app/models/poll_vote.rb
+++ b/app/models/poll_vote.rb
@@ -30,7 +30,7 @@ class PollVote < ApplicationRecord
     return false unless poll
     return false unless poll.vote_previously_recorded_for?(user_id: user_id)
 
-    errors.add(:base, "cannot vote more than once in one poll")
+    errors.add(:base, I18n.t("models.poll_vote.cannot_vote_more_than_once"))
   end
 
   def touch_poll_votes_count
diff --git a/app/models/profile_pin.rb b/app/models/profile_pin.rb
index 8312dc61b..a952ee8fd 100644
--- a/app/models/profile_pin.rb
+++ b/app/models/profile_pin.rb
@@ -14,10 +14,10 @@ class ProfilePin < ApplicationRecord
   private
 
   def only_five_pins_per_profile
-    errors.add(:base, "cannot have more than five total pinned posts") if profile.profile_pins.size > 4
+    errors.add(:base, I18n.t("models.profile_pin.only_five")) if profile.profile_pins.size > 4
   end
 
   def pinnable_belongs_to_profile
-    errors.add(:pinnable_id, "must have proper permissions for pin") if pinnable.user_id != profile_id
+    errors.add(:pinnable_id, I18n.t("models.profile_pin.pin_unpermitted")) if pinnable.user_id != profile_id
   end
 end
diff --git a/app/models/rating_vote.rb b/app/models/rating_vote.rb
index adc41f2ea..d5fed1e7f 100644
--- a/app/models/rating_vote.rb
+++ b/app/models/rating_vote.rb
@@ -22,8 +22,8 @@ class RatingVote < ApplicationRecord
   end
 
   def permissions
-    return if user == article&.user || user&.trusted? || context != "explicit"
+    return unless context == "explicit" && !user&.trusted && user_id != article&.user_id
 
-    errors.add(:user_id, "is not permitted to take this action.")
+    errors.add(:user_id, I18n.t("models.rating_vote.not_permitted"))
   end
 end
diff --git a/app/models/reaction.rb b/app/models/reaction.rb
index ee69393ab..ed8ef0dd0 100644
--- a/app/models/reaction.rb
+++ b/app/models/reaction.rb
@@ -178,9 +178,10 @@ class Reaction < ApplicationRecord
   end
 
   def permissions
-    errors.add(:category, "is not valid.") if negative_reaction_from_untrusted_user?
+    errors.add(:category, I18n.t("models.reaction.is_not_valid")) if negative_reaction_from_untrusted_user?
+    return unless reactable_type == "Article" && !reactable&.published
 
-    errors.add(:reactable_id, "is not valid.") if reactable_type == "Article" && !reactable&.published
+    errors.add(:reactable_id, I18n.t("models.reaction.is_not_valid"))
   end
 
   def negative_reaction_from_untrusted_user?
diff --git a/app/models/response_template.rb b/app/models/response_template.rb
index efa0e24ff..8e2c2e398 100644
--- a/app/models/response_template.rb
+++ b/app/models/response_template.rb
@@ -11,19 +11,18 @@ class ResponseTemplate < ApplicationRecord
   CONTENT_TYPES = %w[plain_text html body_markdown].freeze
   COMMENT_CONTENT_TYPE = %w[body_markdown].freeze
   EMAIL_CONTENT_TYPES = %w[plain_text html].freeze
-  COMMENT_VALIDATION_MSG = "Comment templates must use Markdown as its content type.".freeze
-  EMAIL_VALIDATION_MSG = "Email templates must use plain text or HTML as its content type.".freeze
-  USER_NIL_TYPE_OF_MSG = "cannot have a user ID associated.".freeze
 
   validates :type_of, :content_type, :content, :title, presence: true
   validates :content, uniqueness: { scope: %i[user_id type_of content_type] }
   validates :type_of, inclusion: { in: TYPE_OF_TYPES }
   validates :content_type, inclusion: { in: CONTENT_TYPES }
   validates :content_type,
-            inclusion: { in: COMMENT_CONTENT_TYPE, message: COMMENT_VALIDATION_MSG },
+            inclusion: { in: COMMENT_CONTENT_TYPE,
+                         message: proc { I18n.t("models.response_template.comment_markdown") } },
             if: -> { type_of&.include?("comment") }
   validates :content_type,
-            inclusion: { in: EMAIL_CONTENT_TYPES, message: EMAIL_VALIDATION_MSG },
+            inclusion: { in: EMAIL_CONTENT_TYPES,
+                         message: proc { I18n.t("models.response_template.email_text") } },
             if: -> { type_of&.include?("email") }
   validate :user_nil_only_for_user_nil_types
   validate :template_count
@@ -33,13 +32,13 @@ class ResponseTemplate < ApplicationRecord
   def user_nil_only_for_user_nil_types
     return unless user_id.present? && USER_NIL_TYPE_OF_TYPES.include?(type_of)
 
-    errors.add(:type_of, USER_NIL_TYPE_OF_MSG)
+    errors.add(:type_of, I18n.t("models.response_template.user_nil_only"))
   end
 
   def template_count
     return unless user
-    return if user.trusted? || user.response_templates.count <= 30
+    return if user.trusted || user.response_templates.count <= 30
 
-    errors.add(:user, "Response template limit of 30 per user has been reached")
+    errors.add(:user, I18n.t("models.response_template.limit_reached"))
   end
 end
diff --git a/app/models/settings/campaign.rb b/app/models/settings/campaign.rb
index 35480c865..c25a19685 100644
--- a/app/models/settings/campaign.rb
+++ b/app/models/settings/campaign.rb
@@ -5,7 +5,7 @@ module Settings
     # Define your settings
     setting :articles_expiry_time, type: :integer, default: 4
     setting :articles_require_approval, type: :boolean, default: 0
-    setting :call_to_action, type: :string, default: "Share your project"
+    setting :call_to_action, type: :string, default: -> { I18n.t("models.settings.campaign.share_your_project") }
     setting :featured_tags, type: :array, default: %w[]
     setting :hero_html_variant_name, type: :string, default: ""
     setting :sidebar_enabled, type: :boolean, default: 0
diff --git a/app/models/settings/community.rb b/app/models/settings/community.rb
index 23d941735..0b7f4aa3b 100644
--- a/app/models/settings/community.rb
+++ b/app/models/settings/community.rb
@@ -10,11 +10,11 @@ module Settings
     setting(
       :community_name,
       type: :string,
-      default: ApplicationConfig["COMMUNITY_NAME"] || "New Forem",
+      default: ApplicationConfig["COMMUNITY_NAME"] || I18n.t("models.settings.community.new_forem"),
       validates: {
         format: {
           with: /\A[^[<|>]]+\Z/,
-          message: "may not include the \"<\" nor \">\" character"
+          message: I18n.t("models.settings.community.message")
         }
       },
     )
diff --git a/app/models/settings/general.rb b/app/models/settings/general.rb
index fa26d5083..8cb8fa790 100644
--- a/app/models/settings/general.rb
+++ b/app/models/settings/general.rb
@@ -48,7 +48,9 @@ module Settings
             type: :string,
             default: proc { URL.local_image("mascot.png") },
             validates: { url: true }
-    setting :mascot_image_description, type: :string, default: "The community mascot"
+    setting :mascot_image_description, type: :string, default: lambda {
+                                                                 I18n.t("models.settings.general.the_community_mascot")
+                                                               }
     setting :mascot_footer_image_url, type: :string, validates: { url: true }
     setting :mascot_footer_image_width, type: :integer, default: 52
     setting :mascot_footer_image_height, type: :integer, default: 120
@@ -93,7 +95,7 @@ module Settings
     setting :twitter_hashtag, type: :string
 
     # Sponsors
-    setting :sponsor_headline, default: "Community Sponsors"
+    setting :sponsor_headline, default: -> { I18n.t("models.settings.general.community_sponsors") }
 
     # Tags
     setting :sidebar_tags, type: :array, default: %w[]
diff --git a/app/models/settings/user_experience.rb b/app/models/settings/user_experience.rb
index 65bb5eb53..334d5817d 100644
--- a/app/models/settings/user_experience.rb
+++ b/app/models/settings/user_experience.rb
@@ -21,7 +21,7 @@ module Settings
     setting :primary_brand_color_hex, type: :string, default: "#3b49df", validates: {
       format: {
         with: HEX_COLOR_REGEX,
-        message: "must be be a 3 or 6 character hex (starting with #)"
+        message: proc { I18n.t("models.settings.user_experience.message") }
       },
       color_contrast: true
     }
diff --git a/app/models/sponsorship.rb b/app/models/sponsorship.rb
index 976d5977c..a5361c120 100644
--- a/app/models/sponsorship.rb
+++ b/app/models/sponsorship.rb
@@ -23,7 +23,7 @@ class Sponsorship < ApplicationRecord
   validates :sponsorable_type, inclusion: {
     in: SPONSORABLE_TYPES,
     allow_blank: true,
-    message: "is not a sponsorable type"
+    message: I18n.t("models.sponsorship.invalid_type")
   }
 
   validate :validate_tag_uniqueness, if: proc { level.to_s == "tag" }
@@ -44,13 +44,14 @@ class Sponsorship < ApplicationRecord
     return unless self.class.where(sponsorable: sponsorable, level: :tag)
       .exists?(["expires_at > ? AND id != ?", Time.current, id.to_i])
 
-    errors.add(:level, "The tag is already sponsored")
+    errors.add(:level, I18n.t("models.sponsorship.already_sponsored"))
   end
 
   def validate_level_uniqueness
     return unless self.class.where(organization: organization)
       .exists?(["level IN (?) AND expires_at > ? AND id != ?", METAL_LEVELS, Time.current, id.to_i])
 
-    errors.add(:level, "You can have only one sponsorship of #{METAL_LEVELS.join(', ')}")
+    levels = METAL_LEVELS.map { |l| I18n.t("models.sponsorship.level.#{l}") }.to_sentence(locale: I18n.locale)
+    errors.add(:level, I18n.t("models.sponsorship.only_one_level", levels: levels))
   end
 end
diff --git a/app/models/tag.rb b/app/models/tag.rb
index d153bd271..933a3c2a4 100644
--- a/app/models/tag.rb
+++ b/app/models/tag.rb
@@ -119,7 +119,7 @@ class Tag < ActsAsTaggableOn::Tag
   end
 
   def validate_name
-    errors.add(:name, "is too long (maximum is 30 characters)") if name.length > 30
+    errors.add(:name, I18n.t("errors.messages.too_long", count: 30)) if name.length > 30
     # [:alnum:] is not used here because it supports diacritical characters.
     # If we decide to allow diacritics in the future, we should replace the
     # following regex with [:alnum:].
@@ -258,7 +258,7 @@ class Tag < ActsAsTaggableOn::Tag
   def validate_alias_for
     return if Tag.exists?(name: alias_for)
 
-    errors.add(:tag, "alias_for must refer to an existing tag")
+    errors.add(:tag, I18n.t("models.tag.alias_for"))
   end
 
   def pound_it
diff --git a/app/models/tag_adjustment.rb b/app/models/tag_adjustment.rb
index 9b18bfcc4..79a998814 100644
--- a/app/models/tag_adjustment.rb
+++ b/app/models/tag_adjustment.rb
@@ -1,5 +1,6 @@
 class TagAdjustment < ApplicationRecord
-  validates :tag_name, presence: true, uniqueness: { scope: :article_id, message: "can't be an already adjusted tag" }
+  validates :tag_name, presence: true,
+                       uniqueness: { scope: :article_id, message: I18n.t("models.tag_adjustment.unique") }
   validates :reason_for_adjustment, presence: true
   validates :adjustment_type, inclusion: { in: %w[removal addition] }, presence: true
   validates :status, inclusion: { in: %w[committed pending committed_and_resolvable resolved] }, presence: true
@@ -14,7 +15,7 @@ class TagAdjustment < ApplicationRecord
   private
 
   def user_permissions
-    errors.add(:user_id, "does not have privilege to adjust these tags") unless has_privilege_to_adjust?
+    errors.add(:user_id, I18n.t("models.tag_adjustment.unpermitted")) unless has_privilege_to_adjust?
   end
 
   def has_privilege_to_adjust?
@@ -28,8 +29,10 @@ class TagAdjustment < ApplicationRecord
          tag.casecmp(tag_name).zero?
        end
       errors.add(:tag_id,
-                 "selected for removal is not a current live tag.")
+                 I18n.t("models.tag_adjustment.not_live"))
     end
-    errors.add(:base, "4 tags max per article.") if adjustment_type == "addition" && article.tag_list.count > 3
+    return unless adjustment_type == "addition" && article.tag_list.count > 3
+
+    errors.add(:base, I18n.t("models.tag_adjustment.too_many_tags"))
   end
 end
diff --git a/app/models/tweet.rb b/app/models/tweet.rb
index 2966dd5f3..f5724e431 100644
--- a/app/models/tweet.rb
+++ b/app/models/tweet.rb
@@ -47,7 +47,7 @@ class Tweet < ApplicationRecord
     def fetch(status_id)
       retrieve_and_save_tweet(status_id)
     rescue TwitterClient::Errors::NotFound => e
-      raise e, "Tweet not found"
+      raise e, I18n.t("models.tweet.tweet_not_found")
     end
 
     def retrieve_and_save_tweet(status_id)
diff --git a/app/models/user.rb b/app/models/user.rb
index feb95642a..ba67f822a 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -26,9 +26,6 @@ class User < ApplicationRecord
 
   USERNAME_MAX_LENGTH = 30
   USERNAME_REGEXP = /\A[a-zA-Z0-9_]+\z/
-  MESSAGES = {
-    reserved_username: "username is reserved"
-  }.freeze
   # follow the syntax in https://interledger.org/rfcs/0026-payment-pointers/#payment-pointer-syntax
   PAYMENT_POINTER_REGEXP = %r{
     \A                # start
@@ -141,9 +138,12 @@ class User < ApplicationRecord
   validates :subscribed_to_user_subscriptions_count, presence: true
   validates :unspent_credits_count, presence: true
   validates :username, length: { in: 2..USERNAME_MAX_LENGTH }, format: USERNAME_REGEXP
-  validates :username, presence: true, exclusion: { in: ReservedWords.all, message: MESSAGES[:invalid_username] }
+  validates :username, presence: true, exclusion: {
+    in: ReservedWords.all,
+    message: proc { I18n.t("models.user.username_is_reserved") }
+  }
   validates :username, uniqueness: { case_sensitive: false, message: lambda do |_obj, data|
-    "#{data[:value]} is taken."
+    I18n.t("models.user.is_taken", username: (data[:value]))
   end }, if: :username_changed?
 
   # add validators for provider related usernames
@@ -483,7 +483,7 @@ class User < ApplicationRecord
   end
 
   def non_banished_username
-    errors.add(:username, "has been banished.") if BanishedUser.exists?(username: username)
+    errors.add(:username, I18n.t("models.user.has_been_banished")) if BanishedUser.exists?(username: username)
   end
 
   def subscribe_to_mailchimp_newsletter
@@ -662,7 +662,7 @@ class User < ApplicationRecord
     rate_limiter.track_limit_by_action(:send_email_confirmation)
     rate_limiter.check_limit!(:send_email_confirmation)
   rescue RateLimitChecker::LimitReached => e
-    errors.add(:email, "confirmation could not be sent. #{e.message}")
+    errors.add(:email, I18n.t("models.user.could_not_send", e_message: e.message))
   end
 
   def update_rate_limit
@@ -671,13 +671,13 @@ class User < ApplicationRecord
     rate_limiter.track_limit_by_action(:user_update)
     rate_limiter.check_limit!(:user_update)
   rescue RateLimitChecker::LimitReached => e
-    errors.add(:base, "User could not be saved. #{e.message}")
+    errors.add(:base, I18n.t("models.user.user_could_not_be_saved", e_message: e.message))
   end
 
   def password_matches_confirmation
     return true if password == password_confirmation
 
-    errors.add(:password, "doesn't match password confirmation")
+    errors.add(:password, I18n.t("models.user.password_not_matched"))
   end
 
   def strip_payment_pointer
diff --git a/app/models/user_block.rb b/app/models/user_block.rb
index d11f467a8..0eec8f42b 100644
--- a/app/models/user_block.rb
+++ b/app/models/user_block.rb
@@ -30,7 +30,7 @@ class UserBlock < ApplicationRecord
   private
 
   def blocker_cannot_be_same_as_blocked
-    errors.add(:blocker_id, "can't be the same as the blocked_id") if blocker_id == blocked_id
+    errors.add(:blocker_id, I18n.t("models.user_block.cant_be_the_same")) if blocker_id == blocked_id
   end
 
   def bust_blocker_cache
diff --git a/app/models/user_subscription.rb b/app/models/user_subscription.rb
index 6e025e36f..1c31d63c6 100644
--- a/app/models/user_subscription.rb
+++ b/app/models/user_subscription.rb
@@ -52,7 +52,7 @@ class UserSubscription < ApplicationRecord
     return unless user_subscription_sourceable
     return if liquid_tags_used.include?(UserSubscriptionTag)
 
-    errors.add(:base, "User subscriptions are not enabled for the source.")
+    errors.add(:base, I18n.t("models.user_subscription.not_enabled"))
   end
 
   def liquid_tags_used
@@ -68,7 +68,7 @@ class UserSubscription < ApplicationRecord
   def non_apple_auth_subscriber
     return unless subscriber_email&.end_with?("@privaterelay.appleid.com")
 
-    errors.add(:subscriber_email, "Can't subscribe with an Apple private relay. Please update email.")
+    errors.add(:subscriber_email, I18n.t("models.user_subscription.non_apple"))
   end
 
   def active_user_subscription_source
@@ -88,6 +88,6 @@ class UserSubscription < ApplicationRecord
 
     return if source_active
 
-    errors.add(:base, "Source not found. Please make sure your #{user_subscription_sourceable_type} is active!")
+    errors.add(:base, I18n.t("models.user_subscription.source_not_found", source: user_subscription_sourceable_type))
   end
 end
diff --git a/app/models/users/deleted_user.rb b/app/models/users/deleted_user.rb
index 72824bcd0..7a77653c0 100644
--- a/app/models/users/deleted_user.rb
+++ b/app/models/users/deleted_user.rb
@@ -16,7 +16,7 @@ module Users
     def self.id() = nil
     def self.darker_color() = Color::CompareHex.new(USER_COLORS).brightness
     def self.username() = "[deleted user]"
-    def self.name() = "[Deleted User]"
+    def self.name() = I18n.t("models.users.deleted_user.name")
     def self.summary() = nil
     def self.twitter_username() = nil
     def self.github_username() = nil
diff --git a/app/models/users/setting.rb b/app/models/users/setting.rb
index 91a7174b5..d6902a6f3 100644
--- a/app/models/users/setting.rb
+++ b/app/models/users/setting.rb
@@ -22,7 +22,8 @@ module Users
 
     validates :brand_color1,
               :brand_color2,
-              format: { with: HEX_COLOR_REGEXP, message: "is not a valid hex color" },
+              format: { with: HEX_COLOR_REGEXP,
+                        message: I18n.t("models.users.setting.invalid_hex") },
               allow_nil: true
     validates :experience_level, numericality: { less_than_or_equal_to: 10 }, allow_blank: true
     validates :feed_referential_link, inclusion: { in: [true, false] }
@@ -42,7 +43,7 @@ module Users
 
       valid = Feeds::ValidateUrl.call(feed_url)
 
-      errors.add(:feed_url, "is not a valid RSS/Atom feed") unless valid
+      errors.add(:feed_url, I18n.t("models.users.setting.invalid_rss")) unless valid
     rescue StandardError => e
       errors.add(:feed_url, e.message)
     end
diff --git a/app/services/spam/handler.rb b/app/services/spam/handler.rb
index a0b794bbc..ee22ee0d2 100644
--- a/app/services/spam/handler.rb
+++ b/app/services/spam/handler.rb
@@ -69,7 +69,7 @@ module Spam
         author_id: Settings::General.mascot_user_id,
         noteable: user,
         reason: "automatic_suspend",
-        content: "User suspended for too many spammy interactions, triggered by autovomit.",
+        content: I18n.t("models.comment.suspended_too_many"),
       )
     end
     private_class_method :suspend!
diff --git a/app/views/api/v0/comments/_comment.json.jbuilder b/app/views/api/v0/comments/_comment.json.jbuilder
index d25ff827f..0a4ccc745 100644
--- a/app/views/api/v0/comments/_comment.json.jbuilder
+++ b/app/views/api/v0/comments/_comment.json.jbuilder
@@ -3,10 +3,10 @@ json.id_code comment.id_code_generated
 json.created_at utc_iso_timestamp(comment.created_at)
 
 if comment.deleted?
-  json.body_html "<p>#{Comment::TITLE_DELETED}</p>"
+  json.body_html "<p>#{Comment.title_deleted}</p>"
   json.set! :user, {}
 elsif comment.hidden_by_commentable_user?
-  json.body_html "<p>#{Comment::TITLE_HIDDEN}</p>"
+  json.body_html "<p>#{Comment.title_hidden}</p>"
   json.set! :user, {}
 else
   json.body_html comment.processed_html
diff --git a/config/locales/models/en.yml b/config/locales/models/en.yml
new file mode 100644
index 000000000..47e01aec1
--- /dev/null
+++ b/config/locales/models/en.yml
@@ -0,0 +1,131 @@
+---
+en:
+  models:
+    api_secret:
+      api_limit_reached: API secret limit of 20 per user has been reached
+    application_record:
+      uninferrable: Could not infer a decorator for %{class}.
+    article:
+      a_post_by: A post by %{user_name}
+      video_unpermitted: cannot be added by member without permission
+      video_processing: cannot be set to true if video is still processing
+      cannot_search_tags_for: 'Cannot search tags for: %{tag}'
+      cannot_search_tags_for_tags: 'Cannot search tags for: %{tags}'
+      unique_coauthor: co-author IDs must be unique
+      too_many_tags: exceed the maximum of 4 tags
+      is_too_long: is too long.
+      invalid_date: must be entered in DD/MM/YYYY format with current or past date
+      series_unpermitted: must be one you have permission to post to
+      invalid_coauthor: must be valid user IDs
+      same_author: must not be the same user as the author
+      must_not_have_spaces: must not have spaces
+      published: Published
+      unique_url: has already been taken. Email %{email} for further details.
+      mention_too_many:
+        one: You cannot mention more than %{count} users in a post!
+        other: You cannot mention more than %{count} users in a post!
+    broadcast:
+      single_active: You can only have one active announcement broadcast
+    comment:
+      deleted: "[deleted]"
+      has_been_deleted: "%{type} has been deleted."
+      hidden: "[hidden by post author]"
+      is_not_valid: is not valid.
+      locked: the discussion is locked on this Post
+      type:
+        Article: Article
+        item: item
+        PodcastEpisode: Podcast episode
+      suspended_too_many: User suspended for too many spammy interactions, triggered by autovomit.
+      mention_too_many:
+        one: You cannot mention more than %{count} users in a comment!
+        other: You cannot mention more than %{count} users in a comment!
+    feedback_message:
+      reported: "(you) previously reported this URL."
+    github_issue:
+      issue_comment_not_found: Issue comment %{issue_id} not found
+      issue_not_found: Issue %{issue_id} not found
+    html_variant:
+      no_edits: cannot change once published and approved
+    identity:
+      no_email_msg: No email found. Please relink your %{provider} account to avoid errors.
+    listing:
+      too_many_tags: exceed the maximum of 8 tags
+      too_many_linebreaks: has too many linebreaks. No more than 12 allowed.
+      image_not_allowed: is not allowed to include images.
+      liquid_not_allowed: is not allowed to include liquid tags.
+    mention:
+      is_not_valid: is not valid.
+    organization:
+      integer_only: Integer only. No sign allowed.
+      reserved_word: "%<value>s is a reserved word. Contact site admins for help registering your organization."
+    page:
+      body_must_exist: must exist if body_html or body_json doesn't exist.
+    podcast:
+      slug_is_reserved: slug is reserved
+    podcast_episode_appearance:
+      provided_role_is_not_valid: provided role is not valid
+    poll_skip:
+      cannot_vote_more_than_once: cannot vote more than once in one poll
+    poll_vote:
+      cannot_vote_more_than_once: cannot vote more than once in one poll
+    profile_pin:
+      only_five: cannot have more than five total pinned posts
+      pin_unpermitted: must have proper permissions for pin
+    rating_vote:
+      not_permitted: is not permitted to take this action.
+    reaction:
+      is_not_valid: is not valid.
+    response_template:
+      user_nil_only: cannot have a user ID associated.
+      comment_markdown: Comment templates must use Markdown as its content type.
+      email_text: Email templates must use plain text or HTML as its content type.
+      limit_reached: Response template limit of 30 per user has been reached
+    settings:
+      campaign:
+        share_your_project: Share your project
+      community:
+        message: may not include the "<" nor ">" character
+        new_forem: New Forem
+        user: user
+      general:
+        community_sponsors: Community Sponsors
+        the_community_mascot: The community mascot
+      user_experience:
+        message: 'must be be a 3 or 6 character hex (starting with #)'
+    sponsorship:
+      invalid_type: is not a sponsorable type
+      already_sponsored: The tag is already sponsored
+      only_one_level: You can have only one sponsorship of %{levels}
+      level:
+        gold: gold
+        silver: silver
+        bronze: bronze
+    tag:
+      alias_for: alias_for must refer to an existing tag
+    tag_adjustment:
+      too_many_tags: 4 tags max per article.
+      unpermitted: does not have privilege to adjust these tags
+      not_live: selected for removal is not a current live tag.
+      unique: can't be an already adjusted tag
+    tweet:
+      tweet_not_found: Tweet not found
+    user:
+      could_not_send: confirmation could not be sent. %{e_message}
+      password_not_matched: doesn't match password confirmation
+      has_been_banished: has been banished.
+      is_taken: "%{username} is taken."
+      user_could_not_be_saved: User could not be saved. %{e_message}
+      username_is_reserved: username is reserved
+    user_block:
+      cant_be_the_same: can't be the same as the blocked_id
+    user_subscription:
+      non_apple: Can't subscribe with an Apple private relay. Please update email.
+      source_not_found: Source not found. Please make sure your %{source} is active!
+      not_enabled: User subscriptions are not enabled for the source.
+    users:
+      deleted_user:
+        name: "[Deleted User]"
+      setting:
+        invalid_hex: is not a valid hex color
+        invalid_rss: is not a valid RSS/Atom feed
diff --git a/config/locales/models/fr.yml b/config/locales/models/fr.yml
new file mode 100644
index 000000000..b058d8344
--- /dev/null
+++ b/config/locales/models/fr.yml
@@ -0,0 +1,131 @@
+---
+fr:
+  models:
+    api_secret:
+      api_limit_reached: API secret limit of 20 per user has been reached
+    application_record:
+      uninferrable: Could not infer a decorator for %{class}.
+    article:
+      a_post_by: A post by %{user_name}
+      video_unpermitted: cannot be added by member without permission
+      video_processing: cannot be set to true if video is still processing
+      cannot_search_tags_for: 'Cannot search tags for: %{tag}'
+      cannot_search_tags_for_tags: 'Cannot search tags for: %{tags}'
+      unique_coauthor: co-author IDs must be unique
+      too_many_tags: exceed the maximum of 4 tags
+      is_too_long: is too long.
+      invalid_date: must be entered in DD/MM/YYYY format with current or past date
+      series_unpermitted: must be one you have permission to post to
+      invalid_coauthor: must be valid user IDs
+      same_author: must not be the same user as the author
+      must_not_have_spaces: must not have spaces
+      published: Published
+      unique_url: has already been taken. Email %{email} for further details.
+      mention_too_many:
+        one: You cannot mention more than %{count} users in a post!
+        other: You cannot mention more than %{count} users in a post!
+    broadcast:
+      single_active: You can only have one active announcement broadcast
+    comment:
+      deleted: "[deleted]"
+      has_been_deleted: "%{type} has been deleted."
+      hidden: "[hidden by post author]"
+      is_not_valid: is not valid.
+      locked: the discussion is locked on this Post
+      type:
+        Article: Article
+        item: item
+        PodcastEpisode: Podcast episode
+      suspended_too_many: User suspended for too many spammy interactions, triggered by autovomit.
+      mention_too_many:
+        one: You cannot mention more than %{count} users in a comment!
+        other: You cannot mention more than %{count} users in a comment!
+    feedback_message:
+      reported: "(you) previously reported this URL."
+    github_issue:
+      issue_comment_not_found: Issue comment %{issue_id} not found
+      issue_not_found: Issue %{issue_id} not found
+    html_variant:
+      no_edits: cannot change once published and approved
+    identity:
+      no_email_msg: No email found. Please relink your %{provider} account to avoid errors.
+    listing:
+      too_many_tags: exceed the maximum of 8 tags
+      too_many_linebreaks: has too many linebreaks. No more than 12 allowed.
+      image_not_allowed: is not allowed to include images.
+      liquid_not_allowed: is not allowed to include liquid tags.
+    mention:
+      is_not_valid: is not valid.
+    organization:
+      integer_only: Integer only. No sign allowed.
+      reserved_word: "%<value>s is a reserved word. Contact site admins for help registering your organization."
+    page:
+      body_must_exist: must exist if body_html or body_json doesn't exist.
+    podcast:
+      slug_is_reserved: slug is reserved
+    podcast_episode_appearance:
+      provided_role_is_not_valid: provided role is not valid
+    poll_skip:
+      cannot_vote_more_than_once: cannot vote more than once in one poll
+    poll_vote:
+      cannot_vote_more_than_once: cannot vote more than once in one poll
+    profile_pin:
+      only_five: cannot have more than five total pinned posts
+      pin_unpermitted: must have proper permissions for pin
+    rating_vote:
+      not_permitted: is not permitted to take this action.
+    reaction:
+      is_not_valid: is not valid.
+    response_template:
+      user_nil_only: cannot have a user ID associated.
+      comment_markdown: Comment templates must use Markdown as its content type.
+      email_text: Email templates must use plain text or HTML as its content type.
+      limit_reached: Response template limit of 30 per user has been reached
+    settings:
+      campaign:
+        share_your_project: Share your project
+      community:
+        message: may not include the "<" nor ">" character
+        new_forem: New Forem
+        user: user
+      general:
+        community_sponsors: Community Sponsors
+        the_community_mascot: The community mascot
+      user_experience:
+        message: 'must be be a 3 or 6 character hex (starting with #)'
+    sponsorship:
+      invalid_type: is not a sponsorable type
+      already_sponsored: The tag is already sponsored
+      only_one_level: You can have only one sponsorship of %{levels}
+      level:
+        gold: gold
+        silver: silver
+        bronze: bronze
+    tag:
+      alias_for: alias_for must refer to an existing tag
+    tag_adjustment:
+      too_many_tags: 4 tags max per article.
+      unpermitted: does not have privilege to adjust these tags
+      not_live: selected for removal is not a current live tag.
+      unique: can't be an already adjusted tag
+    tweet:
+      tweet_not_found: Tweet not found
+    user:
+      could_not_send: confirmation could not be sent. %{e_message}
+      password_not_matched: doesn't match password confirmation
+      has_been_banished: has been banished.
+      is_taken: "%{username} is taken."
+      user_could_not_be_saved: User could not be saved. %{e_message}
+      username_is_reserved: username is reserved
+    user_block:
+      cant_be_the_same: can't be the same as the blocked_id
+    user_subscription:
+      non_apple: Can't subscribe with an Apple private relay. Please update email.
+      source_not_found: Source not found. Please make sure your %{source} is active!
+      not_enabled: User subscriptions are not enabled for the source.
+    users:
+      deleted_user:
+        name: "[Deleted User]"
+      setting:
+        invalid_hex: is not a valid hex color
+        invalid_rss: is not a valid RSS/Atom feed
diff --git a/spec/models/feedback_message_spec.rb b/spec/models/feedback_message_spec.rb
index 5f4cbcf2c..d410302e8 100644
--- a/spec/models/feedback_message_spec.rb
+++ b/spec/models/feedback_message_spec.rb
@@ -39,7 +39,7 @@ RSpec.describe FeedbackMessage, type: :model do
       it do
         expect(feedback_message).to validate_uniqueness_of(:reporter_id)
           .scoped_to(described_class::REPORTER_UNIQUENESS_SCOPE)
-          .with_message(described_class::REPORTER_UNIQUENESS_MSG)
+          .with_message(described_class.reporter_uniqueness_msg)
       end
 
       it { is_expected.to validate_length_of(:reported_url).is_at_most(250) }
diff --git a/spec/models/response_template_spec.rb b/spec/models/response_template_spec.rb
index 72ba11a80..e3d02f3d6 100644
--- a/spec/models/response_template_spec.rb
+++ b/spec/models/response_template_spec.rb
@@ -1,7 +1,7 @@
 require "rails_helper"
 
 RSpec.describe ResponseTemplate, type: :model do
-  let(:comment_validation_message) { ResponseTemplate::COMMENT_VALIDATION_MSG }
+  let(:comment_validation_message) { I18n.t("models.response_template.comment_markdown") }
 
   it { is_expected.to validate_inclusion_of(:type_of).in_array(ResponseTemplate::TYPE_OF_TYPES) }
   it { is_expected.to validate_inclusion_of(:content_type).in_array(ResponseTemplate::CONTENT_TYPES) }
@@ -25,7 +25,9 @@ RSpec.describe ResponseTemplate, type: :model do
       it "validates that there is no user ID associated" do
         response_template = build(:response_template, type_of: "mod_comment", content_type: "body_markdown", user_id: 1)
         expect(response_template.valid?).to eq false
-        expect(response_template.errors.messages[:type_of].to_sentence).to eq(ResponseTemplate::USER_NIL_TYPE_OF_MSG)
+        expect(response_template.errors.messages[:type_of].to_sentence).to eq(
+          I18n.t("models.response_template.user_nil_only"),
+        )
       end
     end
   end
diff --git a/spec/requests/admin/response_templates_spec.rb b/spec/requests/admin/response_templates_spec.rb
index 92d27dac2..9e7ac56b4 100644
--- a/spec/requests/admin/response_templates_spec.rb
+++ b/spec/requests/admin/response_templates_spec.rb
@@ -59,7 +59,7 @@ RSpec.describe "/admin/advanced/response_templates", type: :request do
           title: "something"
         }
       }
-      expect(response.body).to include(ResponseTemplate::COMMENT_VALIDATION_MSG)
+      expect(response.body).to include(I18n.t("models.response_template.comment_markdown"))
     end
   end
 
@@ -102,7 +102,7 @@ RSpec.describe "/admin/advanced/response_templates", type: :request do
           content_type: "html"
         }
       }
-      expect(response.body).to include(ResponseTemplate::COMMENT_VALIDATION_MSG)
+      expect(response.body).to include(I18n.t("models.response_template.comment_markdown"))
     end
   end
 
diff --git a/spec/requests/api/v0/comments_spec.rb b/spec/requests/api/v0/comments_spec.rb
index 6b9942297..a8bf130d1 100644
--- a/spec/requests/api/v0/comments_spec.rb
+++ b/spec/requests/api/v0/comments_spec.rb
@@ -118,7 +118,7 @@ RSpec.describe "Api::V0::Comments", type: :request do
       it "replaces the body_html" do
         get api_comments_path(a_id: article.id)
 
-        expect(find_child_comment(response)["body_html"]).to eq("<p>#{Comment::TITLE_DELETED}</p>")
+        expect(find_child_comment(response)["body_html"]).to eq("<p>#{Comment.title_deleted}</p>")
       end
 
       it "does not render the user information" do
@@ -148,7 +148,7 @@ RSpec.describe "Api::V0::Comments", type: :request do
       it "replaces the body_html" do
         get api_comments_path(a_id: article.id)
 
-        expect(find_child_comment(response)["body_html"]).to eq("<p>#{Comment::TITLE_HIDDEN}</p>")
+        expect(find_child_comment(response)["body_html"]).to eq("<p>#{Comment.title_hidden}</p>")
       end
 
       it "does not render the user information" do
diff --git a/spec/services/notifications/new_mention/send_spec.rb b/spec/services/notifications/new_mention/send_spec.rb
index dbc8a01e5..44ff6a273 100644
--- a/spec/services/notifications/new_mention/send_spec.rb
+++ b/spec/services/notifications/new_mention/send_spec.rb
@@ -52,6 +52,7 @@ RSpec.describe Notifications::NewMention::Send, type: :service do
     user.notification_setting.update(mobile_mention_notifications: true)
     allow(PushNotifications::Send).to receive(:call)
     allow(I18n).to receive(:t).with("services.notifications.new_mention.new")
+    allow(I18n).to receive(:l)
     allow(I18n).to receive(:t).with("views.notifications.mention.article_mobile",
                                     user: mention.mentionable.user.username,
                                     title: anything).and_call_original