diff --git a/docs/DEVELOPMENT.md b/docs/DEVELOPMENT.md
index 6dd439ddc7..a20a5db0b0 100644
--- a/docs/DEVELOPMENT.md
+++ b/docs/DEVELOPMENT.md
@@ -90,6 +90,7 @@ development environment configured with the software needed for this project.
 - Once you have successfully set up a development environment, it will be available on http://localhost:3000
 - Log in as the default admin user with the username `admin@mastodon.local` and the password `mastodonadmin`.
 - Check out the [Mastodon docs] for tips on working with emails in development (you'll need this when creating new user accounts) as well as a list of useful commands for testing and updating your dev instance.
+- You can optionally populate your database with sample data by running `bin/rails dev:populate_sample_data`. This will create a `@showcase_account` account with various types of contents.
 
 [codespace]: https://codespaces.new/mastodon/mastodon?quickstart=1&devcontainer_path=.devcontainer%2Fcodespaces%2Fdevcontainer.json
 [CONTRIBUTING]: ../CONTRIBUTING.md
diff --git a/lib/tasks/dev.rake b/lib/tasks/dev.rake
new file mode 100644
index 0000000000..fbb971ba87
--- /dev/null
+++ b/lib/tasks/dev.rake
@@ -0,0 +1,354 @@
+# frozen_string_literal: true
+
+namespace :dev do
+  desc 'Populate database with test data. Can be run multiple times. Should not be run in production environments'
+  task populate_sample_data: :environment do
+    # Create a valid account to showcase multiple post types
+    showcase_account = Account.create_with(username: 'showcase_account').find_or_create_by!(id: 10_000_000)
+    showcase_user = User.create_with(
+      account_id: showcase_account.id,
+      agreement: true,
+      password: SecureRandom.hex,
+      email: ENV.fetch('TEST_DATA_SHOWCASE_EMAIL', 'showcase_account@joinmastodon.org'),
+      confirmed_at: Time.now.utc,
+      approved: true
+    ).find_or_create_by!(id: 10_000_000)
+    showcase_user.mark_email_as_confirmed!
+    showcase_user.approve!
+
+    french_post = Status.create_with(
+      text: 'Ceci est un sondage public écrit en Français',
+      language: 'fr',
+      account: showcase_account,
+      visibility: :public,
+      poll_attributes: {
+        voters_count: 0,
+        account: showcase_account,
+        expires_at: 1.day.from_now,
+        options: ['ceci est un choix', 'ceci est un autre choix'],
+        multiple: false,
+      }
+    ).find_or_create_by!(id: 10_000_000)
+
+    private_mentionless = Status.create_with(
+      text: 'This is a private message written in English',
+      language: 'en',
+      account: showcase_account,
+      visibility: :private
+    ).find_or_create_by!(id: 10_000_001)
+
+    public_self_reply_with_cw = Status.create_with(
+      text: 'This is a public self-reply written in English; it has a CW and a multi-choice poll',
+      spoiler_text: 'poll (CW example)',
+      language: 'en',
+      account: showcase_account,
+      visibility: :public,
+      thread: french_post,
+      poll_attributes: {
+        voters_count: 0,
+        account: showcase_account,
+        expires_at: 1.day.from_now,
+        options: ['this is a choice', 'this is another choice', 'you can chose any number of them'],
+        multiple: true,
+      }
+    ).find_or_create_by!(id: 10_000_002)
+    ProcessHashtagsService.new.call(public_self_reply_with_cw)
+
+    unlisted_self_reply_with_cw_tag_mention = Status.create_with(
+      text: 'This is an unlisted (Quiet Public) self-reply written in #English; it has a CW, mentions @showcase_account, and uses an emoji 🦣',
+      spoiler_text: 'CW example',
+      language: 'en',
+      account: showcase_account,
+      visibility: :unlisted,
+      thread: public_self_reply_with_cw
+    ).find_or_create_by!(id: 10_000_003)
+    Mention.find_or_create_by!(status: unlisted_self_reply_with_cw_tag_mention, account: showcase_account)
+    ProcessHashtagsService.new.call(unlisted_self_reply_with_cw_tag_mention)
+
+    media_attachment = MediaAttachment.create_with(
+      account: showcase_account,
+      file: File.open('spec/fixtures/files/600x400.png'),
+      description: 'Mastodon logo'
+    ).find_or_create_by!(id: 10_000_000)
+    status_with_media = Status.create_with(
+      text: "This is a public status with a picture and tags. The attached picture has an alt text\n\n#Mastodon #Logo #English #Test",
+      ordered_media_attachment_ids: [media_attachment.id],
+      account: showcase_account,
+      visibility: :public
+    ).find_or_create_by!(id: 10_000_004)
+    media_attachment.update(status_id: status_with_media.id)
+    ProcessHashtagsService.new.call(status_with_media)
+
+    media_attachment = MediaAttachment.create_with(
+      account: showcase_account,
+      file: File.open('spec/fixtures/files/600x400.png'),
+      description: 'Mastodon logo'
+    ).find_or_create_by!(id: 10_000_001)
+    status_with_sensitive_media = Status.create_with(
+      text: "This is the same public status with a picture and tags, but it is marked as sensitive. The attached picture has an alt text\n\n#Mastodon #Logo #English #Test",
+      ordered_media_attachment_ids: [media_attachment.id],
+      account: showcase_account,
+      visibility: :public,
+      sensitive: true,
+      thread: status_with_media
+    ).find_or_create_by!(id: 10_000_005)
+    media_attachment.update(status_id: status_with_sensitive_media.id)
+    ProcessHashtagsService.new.call(status_with_sensitive_media)
+
+    media_attachment = MediaAttachment.create_with(
+      account: showcase_account,
+      file: File.open('spec/fixtures/files/600x400.png'),
+      description: 'Mastodon logo'
+    ).find_or_create_by!(id: 10_000_002)
+    status_with_cw_media = Status.create_with(
+      text: "This is the same public status with a picture and tags, but it is behind a CW. The attached picture has an alt text\n\n#Mastodon #Logo #English #Test",
+      spoiler_text: 'Mastodon logo',
+      ordered_media_attachment_ids: [media_attachment.id],
+      account: showcase_account,
+      visibility: :public,
+      sensitive: true,
+      thread: status_with_sensitive_media
+    ).find_or_create_by!(id: 10_000_006)
+    media_attachment.update(status_id: status_with_cw_media.id)
+    ProcessHashtagsService.new.call(status_with_cw_media)
+
+    media_attachment = MediaAttachment.create_with(
+      account: showcase_account,
+      file: File.open('spec/fixtures/files/boop.ogg'),
+      description: 'Mastodon boop'
+    ).find_or_create_by!(id: 10_000_003)
+    status_with_audio = Status.create_with(
+      text: "This is the same public status with an audio file and tags. The attached picture has an alt text\n\n#Mastodon #English #Test",
+      ordered_media_attachment_ids: [media_attachment.id],
+      account: showcase_account,
+      visibility: :public,
+      thread: status_with_cw_media
+    ).find_or_create_by!(id: 10_000_007)
+    media_attachment.update(status_id: status_with_audio.id)
+    ProcessHashtagsService.new.call(status_with_audio)
+
+    media_attachment = MediaAttachment.create_with(
+      account: showcase_account,
+      file: File.open('spec/fixtures/files/boop.ogg'),
+      description: 'Mastodon boop'
+    ).find_or_create_by!(id: 10_000_004)
+    status_with_sensitive_audio = Status.create_with(
+      text: "This is the same public status with an audio file and tags, but it is marked as sensitive. The attached picture has an alt text\n\n#Mastodon #English #Test",
+      ordered_media_attachment_ids: [media_attachment.id],
+      account: showcase_account,
+      visibility: :public,
+      sensitive: true,
+      thread: status_with_audio
+    ).find_or_create_by!(id: 10_000_008)
+    media_attachment.update(status_id: status_with_sensitive_audio.id)
+    ProcessHashtagsService.new.call(status_with_sensitive_audio)
+
+    media_attachment = MediaAttachment.create_with(
+      account: showcase_account,
+      file: File.open('spec/fixtures/files/boop.ogg'),
+      description: 'Mastodon boop'
+    ).find_or_create_by!(id: 10_000_005)
+    status_with_cw_audio = Status.create_with(
+      text: "This is the same public status with an audio file and tags, but it is behind a CW. The attached picture has an alt text\n\n#Mastodon #English #Test",
+      spoiler_text: 'Mastodon boop',
+      ordered_media_attachment_ids: [media_attachment.id],
+      account: showcase_account,
+      visibility: :public,
+      sensitive: true,
+      thread: status_with_sensitive_audio
+    ).find_or_create_by!(id: 10_000_009)
+    media_attachment.update(status_id: status_with_cw_audio.id)
+    ProcessHashtagsService.new.call(status_with_cw_audio)
+
+    media_attachments = [
+      MediaAttachment.create_with(
+        account: showcase_account,
+        file: File.open('spec/fixtures/files/600x400.png'),
+        description: 'Mastodon logo'
+      ).find_or_create_by!(id: 10_000_006),
+      MediaAttachment.create_with(
+        account: showcase_account,
+        file: File.open('spec/fixtures/files/attachment.jpg')
+      ).find_or_create_by!(id: 10_000_007),
+      MediaAttachment.create_with(
+        account: showcase_account,
+        file: File.open('spec/fixtures/files/avatar-high.gif'),
+        description: 'Walking cartoon cat'
+      ).find_or_create_by!(id: 10_000_008),
+      MediaAttachment.create_with(
+        account: showcase_account,
+        file: File.open('spec/fixtures/files/text.png'),
+        description: 'Text saying “Hello Mastodon”'
+      ).find_or_create_by!(id: 10_000_009),
+    ]
+    status_with_multiple_attachments = Status.create_with(
+      text: "This is a post with multiple attachments, not all of which have a description\n\n#Mastodon #English #Test",
+      spoiler_text: 'multiple attachments',
+      ordered_media_attachment_ids: media_attachments.pluck(:id),
+      account: showcase_account,
+      visibility: :public,
+      sensitive: true,
+      thread: status_with_cw_audio
+    ).find_or_create_by!(id: 10_000_010)
+    media_attachments.each { |attachment| attachment.update!(status_id: status_with_multiple_attachments.id) }
+    ProcessHashtagsService.new.call(status_with_multiple_attachments)
+
+    remote_account = Account.create_with(
+      username: 'fake.example',
+      domain: 'example.org',
+      uri: 'https://example.org/foo/bar',
+      url: 'https://example.org/foo/bar',
+      locked: true
+    ).find_or_create_by!(id: 10_000_001)
+
+    remote_formatted_post = Status.create_with(
+      text: <<~HTML,
+        <p>This is a post with a variety of HTML in it</p>
+        <p>For instance, <strong>this text is bold</strong> and <b>this one as well</b>, while <del>this text is stricken through</del> and <s>this one as well</s>.</p>
+        <blockquote>
+          <p>This thing, here, is a block quote<br/>with some <strong>bold</strong> as well</p>
+          <ul>
+            <li>a list item</li>
+            <li>
+              and another with
+              <ul>
+                <li>nested</li>
+                <li>items!</li>
+              </ul>
+            </li>
+          </ul>
+        </blockquote>
+        <pre><code>// And this is some code
+        // with two lines of comments
+        </code></pre>
+        <p>And this is <code>inline</code> code</p>
+        <p>Finally, please observe this Ruby element: <ruby> 明日 <rp>(</rp><rt>Ashita</rt><rp>)</rp> </ruby></p>
+      HTML
+      account: remote_account,
+      uri: 'https://example.org/foo/bar/baz',
+      url: 'https://example.org/foo/bar/baz'
+    ).find_or_create_by!(id: 10_000_011)
+    Status.create_with(account: showcase_account, reblog: remote_formatted_post).find_or_create_by!(id: 10_000_012)
+
+    unattached_quote_post = Status.create_with(
+      text: 'This is a quote of a post that does not exist',
+      account: showcase_account,
+      visibility: :public
+    ).find_or_create_by!(id: 10_000_013)
+    Quote.create_with(
+      status: unattached_quote_post,
+      quoted_status: nil
+    ).find_or_create_by!(id: 10_000_000)
+
+    self_quote = Status.create_with(
+      text: 'This is a quote of a public self-post',
+      account: showcase_account,
+      visibility: :public
+    ).find_or_create_by!(id: 10_000_014)
+    Quote.create_with(
+      status: self_quote,
+      quoted_status: status_with_media,
+      state: :accepted
+    ).find_or_create_by!(id: 10_000_001)
+
+    nested_self_quote = Status.create_with(
+      text: 'This is a quote of a public self-post which itself is a self-quote',
+      account: showcase_account,
+      visibility: :public
+    ).find_or_create_by!(id: 10_000_015)
+    Quote.create_with(
+      status: nested_self_quote,
+      quoted_status: self_quote,
+      state: :accepted
+    ).find_or_create_by!(id: 10_000_002)
+
+    recursive_self_quote = Status.create_with(
+      text: 'This is a recursive self-quote; no real reason for it to exist, but just to make sure we handle them gracefuly',
+      account: showcase_account,
+      visibility: :public
+    ).find_or_create_by!(id: 10_000_016)
+    Quote.create_with(
+      status: recursive_self_quote,
+      quoted_status: recursive_self_quote,
+      state: :accepted
+    ).find_or_create_by!(id: 10_000_003)
+
+    self_private_quote = Status.create_with(
+      text: 'This is a public post of a private self-post: the quoted post should not be visible to non-followers',
+      account: showcase_account,
+      visibility: :public
+    ).find_or_create_by!(id: 10_000_017)
+    Quote.create_with(
+      status: self_private_quote,
+      quoted_status: private_mentionless,
+      state: :accepted
+    ).find_or_create_by!(id: 10_000_004)
+
+    uncwed_quote_cwed = Status.create_with(
+      text: 'This is a quote without CW of a quoted post that has a CW',
+      account: showcase_account,
+      visibility: :public
+    ).find_or_create_by!(id: 10_000_018)
+    Quote.create_with(
+      status: uncwed_quote_cwed,
+      quoted_status: public_self_reply_with_cw,
+      state: :accepted
+    ).find_or_create_by!(id: 10_000_005)
+
+    cwed_quote_cwed = Status.create_with(
+      text: 'This is a quote with a CW of a quoted post that itself has a CW',
+      spoiler_text: 'Quote post with a CW',
+      account: showcase_account,
+      visibility: :public
+    ).find_or_create_by!(id: 10_000_019)
+    Quote.create_with(
+      status: cwed_quote_cwed,
+      quoted_status: public_self_reply_with_cw,
+      state: :accepted
+    ).find_or_create_by!(id: 10_000_006)
+
+    pending_quote_post = Status.create_with(
+      text: 'This quote post is pending',
+      account: showcase_account,
+      visibility: :public
+    ).find_or_create_by!(id: 10_000_020)
+    Quote.create_with(
+      status: pending_quote_post,
+      quoted_status: remote_formatted_post,
+      activity_uri: 'https://foo/bar',
+      state: :pending
+    ).find_or_create_by!(id: 10_000_007)
+
+    rejected_quote_post = Status.create_with(
+      text: 'This quote post is rejected',
+      account: showcase_account,
+      visibility: :public
+    ).find_or_create_by!(id: 10_000_021)
+    Quote.create_with(
+      status: rejected_quote_post,
+      quoted_status: remote_formatted_post,
+      activity_uri: 'https://foo/foo',
+      state: :rejected
+    ).find_or_create_by!(id: 10_000_008)
+
+    revoked_quote_post = Status.create_with(
+      text: 'This quote post is revoked',
+      account: showcase_account,
+      visibility: :public
+    ).find_or_create_by!(id: 10_000_022)
+    Quote.create_with(
+      status: revoked_quote_post,
+      quoted_status: remote_formatted_post,
+      activity_uri: 'https://foo/baz',
+      state: :revoked
+    ).find_or_create_by!(id: 10_000_009)
+
+    StatusPin.create_with(account: showcase_account, status: public_self_reply_with_cw).find_or_create_by!(id: 10_000_000)
+    StatusPin.create_with(account: showcase_account, status: private_mentionless).find_or_create_by!(id: 10_000_001)
+
+    showcase_account.update!(
+      display_name: 'Mastodon test/showcase account',
+      note: 'Test account to showcase many Mastodon features. Most of its posts are public, but some are private!'
+    )
+  end
+end