diff --git a/app/views/about/_logged_in.html.haml b/app/views/about/_logged_in.html.haml
new file mode 100644
index 0000000000..e1bcfffb31
--- /dev/null
+++ b/app/views/about/_logged_in.html.haml
@@ -0,0 +1,10 @@
+.simple_form
+  %p.lead= t('about.logged_in_as_html', username: content_tag(:strong, current_account.username))
+
+  .actions
+    = link_to t('about.continue_to_web'), root_url, class: 'button button-primary'
+
+.form-footer
+  %ul.no-list
+    %li= link_to t('about.get_apps'), 'https://joinmastodon.org/apps', target: '_blank', rel: 'noopener noreferrer'
+    %li= link_to t('auth.logout'), destroy_user_session_path, data: { method: :delete }
diff --git a/app/views/about/_registration.html.haml b/app/views/about/_registration.html.haml
index e4d614d71e..b452e49368 100644
--- a/app/views/about/_registration.html.haml
+++ b/app/views/about/_registration.html.haml
@@ -1,17 +1,20 @@
-.simple_form__overlay-area{ class: (closed_registrations? && @instance_presenter.closed_registrations_message.present?) ? 'simple_form__overlay-area__blurred' : '' }
+- disabled = closed_registrations? || omniauth_only? || current_account.present?
+- show_message = disabled && (current_user.present? || @instance_presenter.closed_registrations_message.present?)
+
+.simple_form__overlay-area{ class: show_message ? 'simple_form__overlay-area__blurred' : '' }
   = simple_form_for(new_user, url: user_registration_path, namespace: 'registration', html: { novalidate: false }) do |f|
     %p.lead= t('about.federation_hint_html', instance: content_tag(:strong, site_hostname))
 
     .fields-group
       = f.simple_fields_for :account do |account_fields|
-        = account_fields.input :username, wrapper: :with_label, label: false, required: true, input_html: { 'aria-label' => t('simple_form.labels.defaults.username'), :autocomplete => 'off', placeholder: t('simple_form.labels.defaults.username'), pattern: '[a-zA-Z0-9_]+', maxlength: 30 }, append: "@#{site_hostname}", hint: false, disabled: closed_registrations?
+        = account_fields.input :username, wrapper: :with_label, label: false, required: true, input_html: { 'aria-label' => t('simple_form.labels.defaults.username'), :autocomplete => 'off', placeholder: t('simple_form.labels.defaults.username'), pattern: '[a-zA-Z0-9_]+', maxlength: 30 }, append: "@#{site_hostname}", hint: false, disabled: disabled
 
-      = f.input :email, placeholder: t('simple_form.labels.defaults.email'), required: true, input_html: { 'aria-label' => t('simple_form.labels.defaults.email'), :autocomplete => 'off' }, hint: false, disabled: closed_registrations?
-      = f.input :password, placeholder: t('simple_form.labels.defaults.password'), required: true, input_html: { 'aria-label' => t('simple_form.labels.defaults.password'), :autocomplete => 'off', :minlength => User.password_length.first, :maxlength => User.password_length.last }, hint: false, disabled: closed_registrations?
-      = f.input :password_confirmation, placeholder: t('simple_form.labels.defaults.confirm_password'), required: true, input_html: { 'aria-label' => t('simple_form.labels.defaults.confirm_password'), :autocomplete => 'off' }, hint: false, disabled: closed_registrations?
+      = f.input :email, placeholder: t('simple_form.labels.defaults.email'), required: true, input_html: { 'aria-label' => t('simple_form.labels.defaults.email'), :autocomplete => 'off' }, hint: false, disabled: disabled
+      = f.input :password, placeholder: t('simple_form.labels.defaults.password'), required: true, input_html: { 'aria-label' => t('simple_form.labels.defaults.password'), :autocomplete => 'off', :minlength => User.password_length.first, :maxlength => User.password_length.last }, hint: false, disabled: disabled
+      = f.input :password_confirmation, placeholder: t('simple_form.labels.defaults.confirm_password'), required: true, input_html: { 'aria-label' => t('simple_form.labels.defaults.confirm_password'), :autocomplete => 'off' }, hint: false, disabled: disabled
 
-      = f.input :confirm_password, as: :string, placeholder: t('simple_form.labels.defaults.honeypot', label: t('simple_form.labels.defaults.password')), required: false, input_html: { 'aria-label' => t('simple_form.labels.defaults.honeypot', label: t('simple_form.labels.defaults.password')), :autocomplete => 'off' }, hint: false, disabled: closed_registrations?
-      = f.input :website, as: :url, placeholder: t('simple_form.labels.defaults.honeypot', label: 'Website'), required: false, input_html: { 'aria-label' => t('simple_form.labels.defaults.honeypot', label: 'Website'), :autocomplete => 'off' }, hint: false, disabled: closed_registrations?
+      = f.input :confirm_password, as: :string, placeholder: t('simple_form.labels.defaults.honeypot', label: t('simple_form.labels.defaults.password')), required: false, input_html: { 'aria-label' => t('simple_form.labels.defaults.honeypot', label: t('simple_form.labels.defaults.password')), :autocomplete => 'off' }, hint: false, disabled: disabled
+      = f.input :website, as: :url, placeholder: t('simple_form.labels.defaults.honeypot', label: 'Website'), required: false, input_html: { 'aria-label' => t('simple_form.labels.defaults.honeypot', label: 'Website'), :autocomplete => 'off' }, hint: false, disabled: disabled
 
     - if approved_registrations?
       .fields-group
@@ -19,13 +22,16 @@
           = invite_request_fields.input :text, as: :text, wrapper: :with_block_label, required: Setting.require_invite_text
 
     .fields-group
-      = f.input :agreement, as: :boolean, wrapper: :with_label, label: t('auth.checkbox_agreement_html', rules_path: about_more_path, terms_path: terms_path), required: true, disabled: closed_registrations?
+      = f.input :agreement, as: :boolean, wrapper: :with_label, label: t('auth.checkbox_agreement_html', rules_path: about_more_path, terms_path: terms_path), required: true, disabled: disabled
 
     .actions
-      = f.button :button, sign_up_message, type: :submit, class: 'button button-primary', disabled: closed_registrations?
+      = f.button :button, sign_up_message, type: :submit, class: 'button button-primary', disabled: disabled
 
-  - if closed_registrations? && @instance_presenter.closed_registrations_message.present?
+  - if show_message
     .simple_form__overlay-area__overlay
       .simple_form__overlay-area__overlay__content.rich-formatting
         .block-icon= fa_icon 'warning'
-        = @instance_presenter.closed_registrations_message.html_safe
+        - if current_account.present?
+          = t('about.logout_before_registering')
+        - else
+          = @instance_presenter.closed_registrations_message.html_safe
diff --git a/app/views/about/show.html.haml b/app/views/about/show.html.haml
index 6ae9e6ae07..3214400960 100644
--- a/app/views/about/show.html.haml
+++ b/app/views/about/show.html.haml
@@ -46,7 +46,10 @@
 
     .landing__grid__column.landing__grid__column-login
       .box-widget
-        = render 'login'
+        - if current_user.present?
+          = render 'logged_in'
+        - else
+          = render 'login'
 
       .hero-widget
         .hero-widget__img
diff --git a/config/locales/en.yml b/config/locales/en.yml
index 6a55941858..98a07aa6a6 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -16,6 +16,7 @@ en:
     contact: Contact
     contact_missing: Not set
     contact_unavailable: N/A
+    continue_to_web: Continue to web app
     discover_users: Discover users
     documentation: Documentation
     federation_hint_html: With an account on %{instance} you'll be able to follow people on any Mastodon server and beyond.
@@ -25,6 +26,8 @@ en:
       This account is a virtual actor used to represent the server itself and not any individual user.
       It is used for federation purposes and should not be blocked unless you want to block the whole instance, in which case you should use a domain block.
     learn_more: Learn more
+    logged_in_as_html: You are currently logged in as %{username}.
+    logout_before_registering: You are already logged in.
     privacy_policy: Privacy policy
     rules: Server rules
     rules_html: 'Below is a summary of rules you need to follow if you want to have an account on this server of Mastodon:'
diff --git a/spec/views/about/show.html.haml_spec.rb b/spec/views/about/show.html.haml_spec.rb
index 1c2f5eee95..4eab97da91 100644
--- a/spec/views/about/show.html.haml_spec.rb
+++ b/spec/views/about/show.html.haml_spec.rb
@@ -8,6 +8,7 @@ describe 'about/show.html.haml', without_verify_partial_doubles: true do
     allow(view).to receive(:site_title).and_return('example site')
     allow(view).to receive(:new_user).and_return(User.new)
     allow(view).to receive(:use_seamless_external_login?).and_return(false)
+    allow(view).to receive(:current_account).and_return(nil)
   end
 
   it 'has valid open graph tags' do