diff --git a/app/controllers/api/base_controller.rb b/app/controllers/api/base_controller.rb
index ac8de5fc0..2bf8e82db 100644
--- a/app/controllers/api/base_controller.rb
+++ b/app/controllers/api/base_controller.rb
@@ -68,7 +68,7 @@ class Api::BaseController < ApplicationController
   end
 
   def require_user!
-    if current_user && !current_user.disabled?
+    if current_user && !current_user.disabled? && current_user.confirmed?
       set_user_activity
     elsif current_user
       render json: { error: 'Your login is currently disabled' }, status: 403
diff --git a/app/controllers/api/v1/accounts_controller.rb b/app/controllers/api/v1/accounts_controller.rb
index f711c4676..1c3e2df8a 100644
--- a/app/controllers/api/v1/accounts_controller.rb
+++ b/app/controllers/api/v1/accounts_controller.rb
@@ -1,13 +1,14 @@
 # frozen_string_literal: true
 
 class Api::V1::AccountsController < Api::BaseController
-  before_action -> { authorize_if_got_token! :read, :'read:accounts' }, except: [:follow, :unfollow, :block, :unblock, :mute, :unmute]
+  before_action -> { authorize_if_got_token! :read, :'read:accounts' }, except: [:create, :follow, :unfollow, :block, :unblock, :mute, :unmute]
   before_action -> { doorkeeper_authorize! :follow, :'write:follows' }, only: [:follow, :unfollow]
   before_action -> { doorkeeper_authorize! :follow, :'write:mutes' }, only: [:mute, :unmute]
   before_action -> { doorkeeper_authorize! :follow, :'write:blocks' }, only: [:block, :unblock]
+  before_action -> { doorkeeper_authorize! }, only: [:create]
 
-  before_action :require_user!, except: [:show]
-  before_action :set_account
+  before_action :require_user!, except: [:show, :create]
+  before_action :set_account, except: [:create]
   before_action :check_account_suspension, only: [:show]
 
   respond_to :json
@@ -16,6 +17,16 @@ class Api::V1::AccountsController < Api::BaseController
     render json: @account, serializer: REST::AccountSerializer
   end
 
+  def create
+    token    = AppSignUpService.new.call(doorkeeper_token.application, account_params)
+    response = Doorkeeper::OAuth::TokenResponse.new(token)
+
+    headers.merge!(response.headers)
+
+    self.response_body = Oj.dump(response.body)
+    self.status        = response.status
+  end
+
   def follow
     FollowService.new.call(current_user.account, @account, reblogs: truthy_param?(:reblogs))
 
@@ -62,4 +73,8 @@ class Api::V1::AccountsController < Api::BaseController
   def check_account_suspension
     gone if @account.suspended?
   end
+
+  def account_params
+    params.permit(:username, :email, :password)
+  end
 end
diff --git a/app/services/app_sign_up_service.rb b/app/services/app_sign_up_service.rb
new file mode 100644
index 000000000..09372b8c2
--- /dev/null
+++ b/app/services/app_sign_up_service.rb
@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+class AppSignUpService < BaseService
+  def call(app, params)
+    return unless allowed_registrations?
+
+    user_params    = params.slice(:email, :password)
+    account_params = params.slice(:username)
+    user           = User.create!(user_params.merge(password_confirmation: user_params[:password], account_attributes: account_params))
+
+    Doorkeeper::AccessToken.create!(application: app,
+                                    resource_owner_id: user.id,
+                                    scopes: app.scopes,
+                                    expires_in: Doorkeeper.configuration.access_token_expires_in,
+                                    use_refresh_token: Doorkeeper.configuration.refresh_token_enabled?)
+  end
+
+  private
+
+  def allowed_registrations?
+    Setting.open_registrations && !Rails.configuration.x.single_user_mode
+  end
+end
diff --git a/config/initializers/rack_attack.rb b/config/initializers/rack_attack.rb
index 8756b8fbf..35302e37b 100644
--- a/config/initializers/rack_attack.rb
+++ b/config/initializers/rack_attack.rb
@@ -57,6 +57,10 @@ class Rack::Attack
     req.authenticated_user_id if req.post? && req.path.start_with?('/api/v1/media')
   end
 
+  throttle('throttle_api_sign_up', limit: 5, period: 30.minutes) do |req|
+    req.ip if req.post? && req.path == '/api/v1/accounts'
+  end
+
   throttle('protected_paths', limit: 25, period: 5.minutes) do |req|
     req.ip if req.post? && req.path =~ PROTECTED_PATHS_REGEX
   end
diff --git a/config/routes.rb b/config/routes.rb
index 0aba433e2..1a37fe361 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -328,7 +328,7 @@ Rails.application.routes.draw do
         resources :relationships, only: :index
       end
 
-      resources :accounts, only: [:show] do
+      resources :accounts, only: [:create, :show] do
         resources :statuses, only: :index, controller: 'accounts/statuses'
         resources :followers, only: :index, controller: 'accounts/follower_accounts'
         resources :following, only: :index, controller: 'accounts/following_accounts'
diff --git a/spec/services/app_sign_up_service_spec.rb b/spec/services/app_sign_up_service_spec.rb
new file mode 100644
index 000000000..867bc621c
--- /dev/null
+++ b/spec/services/app_sign_up_service_spec.rb
@@ -0,0 +1,41 @@
+require 'rails_helper'
+
+RSpec.describe AppSignUpService, type: :service do
+  let(:app) { Fabricate(:application, scopes: 'read write') }
+  let(:good_params) { { username: 'alice', password: '12345678', email: 'good@email.com' } }
+
+  subject { described_class.new }
+
+  describe '#call' do
+    it 'returns nil when registrations are closed' do
+      Setting.open_registrations = false
+      expect(subject.call(app, good_params)).to be_nil
+    end
+
+    it 'raises an error when params are missing' do
+      expect { subject.call(app, {}) }.to raise_error ActiveRecord::RecordInvalid
+    end
+
+    it 'creates an unconfirmed user with access token' do
+      access_token = subject.call(app, good_params)
+      expect(access_token).to_not be_nil
+      user = User.find_by(id: access_token.resource_owner_id)
+      expect(user).to_not be_nil
+      expect(user.confirmed?).to be false
+    end
+
+    it 'creates access token with the app\'s scopes' do
+      access_token = subject.call(app, good_params)
+      expect(access_token).to_not be_nil
+      expect(access_token.scopes.to_s).to eq 'read write'
+    end
+
+    it 'creates an account' do
+      access_token = subject.call(app, good_params)
+      expect(access_token).to_not be_nil
+      user = User.find_by(id: access_token.resource_owner_id)
+      expect(user).to_not be_nil
+      expect(user.account).to_not be_nil
+    end
+  end
+end