diff --git a/app/controllers/api/v1/instances/languages_controller.rb b/app/controllers/api/v1/instances/languages_controller.rb
new file mode 100644
index 000000000..17509e748
--- /dev/null
+++ b/app/controllers/api/v1/instances/languages_controller.rb
@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+class Api::V1::Instances::LanguagesController < Api::BaseController
+  skip_before_action :require_authenticated_user!, unless: :limited_federation_mode?
+  skip_around_action :set_locale
+
+  before_action :set_languages
+
+  vary_by ''
+
+  def show
+    cache_even_if_authenticated!
+    render json: @languages, each_serializer: REST::LanguageSerializer
+  end
+
+  private
+
+  def set_languages
+    @languages = LanguagesHelper::SUPPORTED_LOCALES.keys.map { |code| LanguagePresenter.new(code) }
+  end
+end
diff --git a/app/javascript/packs/sign_up.js b/app/javascript/packs/sign_up.js
index 9aae9c11b..cf9c83777 100644
--- a/app/javascript/packs/sign_up.js
+++ b/app/javascript/packs/sign_up.js
@@ -13,4 +13,30 @@ ready(() => {
       console.error(error);
     });
   }, 5000);
+
+  document.querySelectorAll('.timer-button').forEach(button => {
+    let counter = 30;
+
+    const container = document.createElement('span');
+
+    const updateCounter = () => {
+      container.innerText = ` (${counter})`;
+    };
+
+    updateCounter();
+
+    const countdown = setInterval(() => {
+      counter--;
+
+      if (counter === 0) {
+        button.disabled = false;
+        button.removeChild(container);
+        clearInterval(countdown);
+      } else {
+        updateCounter();
+      }
+    }, 1000);
+
+    button.appendChild(container);
+  });
 });
diff --git a/app/lib/request.rb b/app/lib/request.rb
index adc9a48f3..e5a9476a8 100644
--- a/app/lib/request.rb
+++ b/app/lib/request.rb
@@ -346,7 +346,7 @@ class Request
       end
 
       def private_address_exceptions
-        @private_address_exceptions = (ENV['ALLOWED_PRIVATE_ADDRESSES'] || '').split(',').map { |addr| IPAddr.new(addr) }
+        @private_address_exceptions = (ENV['ALLOWED_PRIVATE_ADDRESSES'] || '').split(/(?:\s*,\s*|\s+)/).map { |addr| IPAddr.new(addr) }
       end
     end
   end
diff --git a/app/presenters/language_presenter.rb b/app/presenters/language_presenter.rb
new file mode 100644
index 000000000..69ea991d5
--- /dev/null
+++ b/app/presenters/language_presenter.rb
@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+class LanguagePresenter < ActiveModelSerializers::Model
+  attributes :code, :name, :native_name
+
+  def initialize(code)
+    super()
+
+    @code = code
+    @item = LanguagesHelper::SUPPORTED_LOCALES[code]
+  end
+
+  def name
+    @item[0]
+  end
+
+  def native_name
+    @item[1]
+  end
+end
diff --git a/app/serializers/rest/language_serializer.rb b/app/serializers/rest/language_serializer.rb
new file mode 100644
index 000000000..e07956465
--- /dev/null
+++ b/app/serializers/rest/language_serializer.rb
@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+class REST::LanguageSerializer < ActiveModel::Serializer
+  attributes :code, :name
+end
diff --git a/app/services/fetch_link_card_service.rb b/app/services/fetch_link_card_service.rb
index 886582460..13775e63c 100644
--- a/app/services/fetch_link_card_service.rb
+++ b/app/services/fetch_link_card_service.rb
@@ -61,9 +61,13 @@ class FetchLinkCardService < BaseService
   end
 
   def attach_card
-    @status.preview_cards << @card
-    Rails.cache.delete(@status)
-    Trends.links.register(@status)
+    with_redis_lock("attach_card:#{@status.id}") do
+      return if @status.preview_cards.any?
+
+      @status.preview_cards << @card
+      Rails.cache.delete(@status)
+      Trends.links.register(@status)
+    end
   end
 
   def parse_urls
diff --git a/app/views/auth/setup/show.html.haml b/app/views/auth/setup/show.html.haml
index 913b0c913..ab9b00bed 100644
--- a/app/views/auth/setup/show.html.haml
+++ b/app/views/auth/setup/show.html.haml
@@ -17,6 +17,6 @@
     = f.input :email, required: true, hint: false, input_html: { 'aria-label': t('simple_form.labels.defaults.email'), autocomplete: 'off' }
 
   .actions
-    = f.submit t('auth.resend_confirmation'), class: 'button'
+    = f.button :button, t('auth.resend_confirmation'), type: :submit, class: 'button timer-button', disabled: true
 
 .form-footer= render 'auth/shared/links'
diff --git a/app/workers/scheduler/follow_recommendations_scheduler.rb b/app/workers/scheduler/follow_recommendations_scheduler.rb
index 17cf3f2cc..ea59ad986 100644
--- a/app/workers/scheduler/follow_recommendations_scheduler.rb
+++ b/app/workers/scheduler/follow_recommendations_scheduler.rb
@@ -4,7 +4,7 @@ class Scheduler::FollowRecommendationsScheduler
   include Sidekiq::Worker
   include Redisable
 
-  sidekiq_options retry: 0
+  sidekiq_options retry: 0, lock: :until_executed, lock_ttl: 1.day.to_i
 
   # The maximum number of accounts that can be requested in one page from the
   # API is 80, and the suggestions API does not allow pagination. This number
diff --git a/app/workers/scheduler/indexing_scheduler.rb b/app/workers/scheduler/indexing_scheduler.rb
index d622f5586..2868a3b71 100644
--- a/app/workers/scheduler/indexing_scheduler.rb
+++ b/app/workers/scheduler/indexing_scheduler.rb
@@ -4,7 +4,7 @@ class Scheduler::IndexingScheduler
   include Sidekiq::Worker
   include Redisable
 
-  sidekiq_options retry: 0
+  sidekiq_options retry: 0, lock: :until_executed, lock_ttl: 1.day.to_i
 
   IMPORT_BATCH_SIZE = 1000
   SCAN_BATCH_SIZE = 10 * IMPORT_BATCH_SIZE
@@ -16,9 +16,7 @@ class Scheduler::IndexingScheduler
       with_redis do |redis|
         redis.sscan_each("chewy:queue:#{type.name}", count: SCAN_BATCH_SIZE).each_slice(IMPORT_BATCH_SIZE) do |ids|
           type.import!(ids)
-          redis.pipelined do |pipeline|
-            pipeline.srem("chewy:queue:#{type.name}", ids)
-          end
+          redis.srem("chewy:queue:#{type.name}", ids)
         end
       end
     end
diff --git a/app/workers/scheduler/instance_refresh_scheduler.rb b/app/workers/scheduler/instance_refresh_scheduler.rb
index 59f91dc62..818682a5d 100644
--- a/app/workers/scheduler/instance_refresh_scheduler.rb
+++ b/app/workers/scheduler/instance_refresh_scheduler.rb
@@ -3,7 +3,7 @@
 class Scheduler::InstanceRefreshScheduler
   include Sidekiq::Worker
 
-  sidekiq_options retry: 0
+  sidekiq_options retry: 0, lock: :until_executed, lock_ttl: 1.day.to_i
 
   def perform
     Instance.refresh
diff --git a/app/workers/scheduler/ip_cleanup_scheduler.rb b/app/workers/scheduler/ip_cleanup_scheduler.rb
index 8f607db03..f78c0584d 100644
--- a/app/workers/scheduler/ip_cleanup_scheduler.rb
+++ b/app/workers/scheduler/ip_cleanup_scheduler.rb
@@ -6,7 +6,7 @@ class Scheduler::IpCleanupScheduler
   IP_RETENTION_PERIOD = ENV.fetch('IP_RETENTION_PERIOD', 1.year).to_i.seconds.freeze
   SESSION_RETENTION_PERIOD = ENV.fetch('SESSION_RETENTION_PERIOD', 1.year).to_i.seconds.freeze
 
-  sidekiq_options retry: 0
+  sidekiq_options retry: 0, lock: :until_executed, lock_ttl: 1.day.to_i
 
   def perform
     clean_ip_columns!
diff --git a/app/workers/scheduler/pghero_scheduler.rb b/app/workers/scheduler/pghero_scheduler.rb
index a756b13b9..49bf2db7a 100644
--- a/app/workers/scheduler/pghero_scheduler.rb
+++ b/app/workers/scheduler/pghero_scheduler.rb
@@ -3,7 +3,7 @@
 class Scheduler::PgheroScheduler
   include Sidekiq::Worker
 
-  sidekiq_options retry: 0
+  sidekiq_options retry: 0, lock: :until_executed, lock_ttl: 1.day.to_i
 
   def perform
     PgHero.capture_space_stats
diff --git a/app/workers/scheduler/scheduled_statuses_scheduler.rb b/app/workers/scheduler/scheduled_statuses_scheduler.rb
index 3bf6300b3..b5801248f 100644
--- a/app/workers/scheduler/scheduled_statuses_scheduler.rb
+++ b/app/workers/scheduler/scheduled_statuses_scheduler.rb
@@ -3,7 +3,7 @@
 class Scheduler::ScheduledStatusesScheduler
   include Sidekiq::Worker
 
-  sidekiq_options retry: 0
+  sidekiq_options retry: 0, lock: :until_executed, lock_ttl: 1.day.to_i
 
   def perform
     publish_scheduled_statuses!
diff --git a/app/workers/scheduler/suspended_user_cleanup_scheduler.rb b/app/workers/scheduler/suspended_user_cleanup_scheduler.rb
index 87e22161b..90feead67 100644
--- a/app/workers/scheduler/suspended_user_cleanup_scheduler.rb
+++ b/app/workers/scheduler/suspended_user_cleanup_scheduler.rb
@@ -16,7 +16,7 @@ class Scheduler::SuspendedUserCleanupScheduler
   # has the capacity for it.
   MAX_DELETIONS_PER_JOB = 10
 
-  sidekiq_options retry: 0
+  sidekiq_options retry: 0, lock: :until_executed, lock_ttl: 1.day.to_i
 
   def perform
     return if Sidekiq::Queue.new('pull').size > MAX_PULL_SIZE
diff --git a/app/workers/scheduler/user_cleanup_scheduler.rb b/app/workers/scheduler/user_cleanup_scheduler.rb
index 4aee7935a..2d2efc731 100644
--- a/app/workers/scheduler/user_cleanup_scheduler.rb
+++ b/app/workers/scheduler/user_cleanup_scheduler.rb
@@ -3,7 +3,7 @@
 class Scheduler::UserCleanupScheduler
   include Sidekiq::Worker
 
-  sidekiq_options retry: 0
+  sidekiq_options retry: 0, lock: :until_executed, lock_ttl: 1.day.to_i
 
   def perform
     clean_unconfirmed_accounts!
diff --git a/app/workers/scheduler/vacuum_scheduler.rb b/app/workers/scheduler/vacuum_scheduler.rb
index 9c040f6e4..1c9a2aabe 100644
--- a/app/workers/scheduler/vacuum_scheduler.rb
+++ b/app/workers/scheduler/vacuum_scheduler.rb
@@ -3,7 +3,7 @@
 class Scheduler::VacuumScheduler
   include Sidekiq::Worker
 
-  sidekiq_options retry: 0, lock: :until_executed
+  sidekiq_options retry: 0, lock: :until_executed, lock_ttl: 1.day.to_i
 
   def perform
     vacuum_operations.each do |operation|
diff --git a/config/routes/api.rb b/config/routes/api.rb
index 207591e99..72815b467 100644
--- a/config/routes/api.rb
+++ b/config/routes/api.rb
@@ -121,6 +121,7 @@ namespace :api, format: false do
       resource :privacy_policy, only: [:show], controller: 'instances/privacy_policies'
       resource :extended_description, only: [:show], controller: 'instances/extended_descriptions'
       resource :translation_languages, only: [:show], controller: 'instances/translation_languages'
+      resource :languages, only: [:show], controller: 'instances/languages'
       resource :activity, only: [:show], controller: 'instances/activity'
     end
 
diff --git a/config/sidekiq.yml b/config/sidekiq.yml
index 2278329a5..12c45c22a 100644
--- a/config/sidekiq.yml
+++ b/config/sidekiq.yml
@@ -23,7 +23,7 @@
       class: Scheduler::Trends::ReviewNotificationsScheduler
       queue: scheduler
     indexing_scheduler:
-      every: '5m'
+      interval: 1 minute
       class: Scheduler::IndexingScheduler
       queue: scheduler
     vacuum_scheduler:
diff --git a/db/post_migrate/20230803082451_add_unique_index_on_preview_cards_statuses.rb b/db/post_migrate/20230803082451_add_unique_index_on_preview_cards_statuses.rb
new file mode 100644
index 000000000..936d7840e
--- /dev/null
+++ b/db/post_migrate/20230803082451_add_unique_index_on_preview_cards_statuses.rb
@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+class AddUniqueIndexOnPreviewCardsStatuses < ActiveRecord::Migration[6.1]
+  disable_ddl_transaction!
+
+  def up
+    add_index :preview_cards_statuses, [:status_id, :preview_card_id], name: :preview_cards_statuses_pkey, algorithm: :concurrently, unique: true
+  rescue ActiveRecord::RecordNotUnique
+    deduplicate_and_reindex!
+  end
+
+  def down
+    remove_index :preview_cards_statuses, name: :preview_cards_statuses_pkey
+  end
+
+  private
+
+  def deduplicate_and_reindex!
+    deduplicate_preview_cards!
+
+    safety_assured { execute 'REINDEX INDEX preview_cards_statuses_pkey' }
+  rescue ActiveRecord::RecordNotUnique
+    retry
+  end
+
+  def deduplicate_preview_cards!
+    # Statuses should have only one preview card at most, even if that's not the database
+    # constraint we will end up with
+    duplicate_ids = select_all('SELECT status_id FROM preview_cards_statuses GROUP BY status_id HAVING count(*) > 1;').rows
+
+    duplicate_ids.each_slice(1000) do |ids|
+      # This one is tricky: since we don't have primary keys to keep only one record,
+      # use the physical `ctid`
+      safety_assured do
+        execute "DELETE FROM preview_cards_statuses p WHERE p.status_id IN (#{ids.join(', ')}) AND p.ctid NOT IN (SELECT q.ctid FROM preview_cards_statuses q WHERE q.status_id = p.status_id LIMIT 1)"
+      end
+    end
+  end
+end
diff --git a/db/post_migrate/20230803112520_add_primary_key_to_preview_cards_statuses_join_table.rb b/db/post_migrate/20230803112520_add_primary_key_to_preview_cards_statuses_join_table.rb
new file mode 100644
index 000000000..34877ac67
--- /dev/null
+++ b/db/post_migrate/20230803112520_add_primary_key_to_preview_cards_statuses_join_table.rb
@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+class AddPrimaryKeyToPreviewCardsStatusesJoinTable < ActiveRecord::Migration[6.1]
+  disable_ddl_transaction!
+
+  def up
+    safety_assured do
+      execute 'ALTER TABLE preview_cards_statuses ADD PRIMARY KEY USING INDEX preview_cards_statuses_pkey'
+    end
+  end
+
+  def down
+    safety_assured do
+      # I have found no way to demote the primary key to an index, instead, re-create the index
+      execute 'CREATE UNIQUE INDEX CONCURRENTLY preview_cards_statuses_pkey_tmp ON preview_cards_statuses (status_id, preview_card_id)'
+      execute 'ALTER TABLE preview_cards_statuses DROP CONSTRAINT preview_cards_statuses_pkey'
+      execute 'ALTER INDEX preview_cards_statuses_pkey_tmp RENAME TO preview_cards_statuses_pkey'
+    end
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 5bfbdb45b..5bce2a2fd 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[7.0].define(version: 2023_07_24_160715) do
+ActiveRecord::Schema[7.0].define(version: 2023_08_03_112520) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
 
@@ -805,7 +805,7 @@ ActiveRecord::Schema[7.0].define(version: 2023_07_24_160715) do
     t.index ["url"], name: "index_preview_cards_on_url", unique: true
   end
 
-  create_table "preview_cards_statuses", id: false, force: :cascade do |t|
+  create_table "preview_cards_statuses", primary_key: ["status_id", "preview_card_id"], force: :cascade do |t|
     t.bigint "preview_card_id", null: false
     t.bigint "status_id", null: false
     t.index ["status_id", "preview_card_id"], name: "index_preview_cards_statuses_on_status_id_and_preview_card_id"
diff --git a/lib/tasks/tests.rake b/lib/tasks/tests.rake
index 3c88ce450..ef4d46fe0 100644
--- a/lib/tasks/tests.rake
+++ b/lib/tasks/tests.rake
@@ -63,6 +63,11 @@ namespace :tests do
         puts 'Account domains not properly normalized'
         exit(1)
       end
+
+      unless Status.find(12).preview_cards.pluck(:url) == ['https://joinmastodon.org/']
+        puts 'Preview cards not deduplicated as expected'
+        exit(1)
+      end
     end
 
     desc 'Populate the database with test data for 2.4.3'
@@ -238,6 +243,11 @@ namespace :tests do
           (10, 2, '@admin hey!', NULL, 1, 3, now(), now()),
           (11, 1, '@user hey!', 10, 1, 3, now(), now());
 
+        INSERT INTO "statuses"
+          (id, account_id, text, created_at, updated_at)
+        VALUES
+          (12, 1, 'check out https://joinmastodon.org/', now(), now());
+
         -- mentions (from previous statuses)
 
         INSERT INTO "mentions"
@@ -326,6 +336,21 @@ namespace :tests do
           (1, 6, 2, 'Follow', 2, now(), now()),
           (2, 2, 1, 'Mention', 4, now(), now()),
           (3, 1, 2, 'Mention', 5, now(), now());
+
+        -- preview cards
+
+        INSERT INTO "preview_cards"
+          (id, url, title, created_at, updated_at)
+        VALUES
+          (1, 'https://joinmastodon.org/', 'Mastodon - Decentralized social media', now(), now());
+
+        -- many-to-many association between preview cards and statuses
+
+        INSERT INTO "preview_cards_statuses"
+          (status_id, preview_card_id)
+        VALUES
+          (12, 1),
+          (12, 1);
       SQL
     end
   end
diff --git a/spec/requests/api/v1/instances/languages_spec.rb b/spec/requests/api/v1/instances/languages_spec.rb
new file mode 100644
index 000000000..8ab8bf99c
--- /dev/null
+++ b/spec/requests/api/v1/instances/languages_spec.rb
@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe 'Languages' do
+  describe 'GET /api/v1/instance/languages' do
+    before do
+      get '/api/v1/instance/languages'
+    end
+
+    it 'returns http success' do
+      expect(response).to have_http_status(200)
+    end
+
+    it 'returns the supported languages' do
+      expect(body_as_json.pluck(:code)).to match_array LanguagesHelper::SUPPORTED_LOCALES.keys.map(&:to_s)
+    end
+  end
+end