diff --git a/app/api/api_v1/auth/jwt_authenticator.rb b/app/api/api_v1/auth/jwt_authenticator.rb
index fa7b833..6e0e999 100644
--- a/app/api/api_v1/auth/jwt_authenticator.rb
+++ b/app/api/api_v1/auth/jwt_authenticator.rb
@@ -9,18 +9,14 @@ def initialize(token)
 
       #
       # Decodes and verifies JWT.
-      # Returns authentic member email or raises an exception.
+      # Returns hash formed with payload including user id (uid) or raises an exception.
       #
-      # @param [Hash] options
-      # @return [String, User, NilClass]
-      def authenticate!(options = {})
-        unless @token_type == 'Bearer'
-          raise AuthorizationError, 'Token type is not provided or invalid.'
-        end
+      # @return [Hash, NilClass]
+      def authenticate!
+        check_token_type
         payload, _header = decode_and_verify_token(@token_value)
-        fetch_user(payload).yield_self do |user|
-          options[:return] == :user ? user : fetch_uid(payload)
-        end
+
+        { uid: fetch_uid(payload) }
       rescue => e
         report_exception(e)
         if AuthorizationError === e
@@ -33,14 +29,20 @@ def authenticate!(options = {})
       #
       # Exception-safe version of #authenticate!.
       #
-      # @return [String, User, NilClass]
+      # @return [Hash, NilClass]
       def authenticate(*args)
         authenticate!(*args)
       rescue
         nil
       end
 
-    private
+      private
+
+      def check_token_type
+        unless @token_type == 'Bearer'
+          raise AuthorizationError, 'Token type is not provided or invalid.'
+        end
+      end
 
       def decode_and_verify_token(token)
         JWT.decode(token, Utils.jwt_public_key, true, token_verification_options)
@@ -49,49 +51,12 @@ def decode_and_verify_token(token)
         raise AuthorizationError, "Failed to decode and verify JWT: #{e.inspect}."
       end
 
-      def fetch_email(payload)
-        payload[:email].to_s.tap do |email|
-          raise(AuthorizationError, 'E-Mail is blank.') if email.blank?
-          raise(AuthorizationError, 'E-Mail is invalid.') unless EmailValidator.valid?(email)
-        end
-      end
-
       def fetch_uid(payload)
         payload.fetch(:uid).tap do |uid|
           raise(AuthorizationError, 'UID is blank.') if uid.blank?
         end
       end
 
-      def fetch_scopes(payload)
-        Array.wrap(payload[:scopes]).map(&:to_s).map(&:squash).reject(&:blank).tap do |scopes|
-          raise(AuthorizationError, 'Token scopes are not defined.') if scopes.empty?
-        end
-      end
-
-      def fetch_user(payload)
-        if payload[:iss] == 'barong'
-          from_barong_payload(payload)
-        else
-          User.find_by(uid: fetch_uid(payload))
-        end
-      end
-
-      def from_barong_payload(payload)
-        User.find_or_initialize_by(uid: fetch_uid(payload)).tap do |member|
-          member.transaction do
-            attributes = {
-              email: fetch_email(payload),
-              state: payload.fetch(:state).to_s,
-              level: payload.fetch(:level).to_i
-            }
-
-            # Prevent overheat validations.
-            member.assign_attributes(attributes)
-            member.save!(validate: member.new_record?)
-          end
-        end
-      end
-
       def token_verification_options
         { verify_expiration: true,
           verify_not_before: true,
diff --git a/app/api/api_v1/auth/middleware.rb b/app/api/api_v1/auth/middleware.rb
index b2a5e67..6dc60f3 100644
--- a/app/api/api_v1/auth/middleware.rb
+++ b/app/api/api_v1/auth/middleware.rb
@@ -6,8 +6,8 @@ class Middleware < Grape::Middleware::Base
       def before
         return unless auth_by_jwt?
 
-        env['api.v1.authenticated_uid'] = \
-          JWTAuthenticator.new(headers['Authorization']).authenticate!(return: :uid)
+        env['api.v1.authenticated_data'] = \
+          JWTAuthenticator.new(headers['Authorization']).authenticate!
       end
 
       private
diff --git a/app/api/api_v1/base.rb b/app/api/api_v1/base.rb
index a3d3020..c702aa1 100644
--- a/app/api/api_v1/base.rb
+++ b/app/api/api_v1/base.rb
@@ -19,7 +19,7 @@ class Base < Grape::API
                               doc_version: '0.0.1',
                               info: {
                                 title: 'User API V1',
-                                description: 'User API is client-to-server API'
+                                description: 'User API is client-to-server API v.1'
                               },
                               hide_format: true,
                               hide_documentation_path: true
diff --git a/app/api/api_v1/cors/middleware.rb b/app/api/api_v1/cors/middleware.rb
index d556846..1b78247 100644
--- a/app/api/api_v1/cors/middleware.rb
+++ b/app/api/api_v1/cors/middleware.rb
@@ -36,7 +36,7 @@ def call(env)
         end
       end
 
-    private
+      private
 
       def request
         @request ||= Grape::Request.new(env)
diff --git a/app/api/api_v1/helpers.rb b/app/api/api_v1/helpers.rb
index 994eae2..224844f 100644
--- a/app/api/api_v1/helpers.rb
+++ b/app/api/api_v1/helpers.rb
@@ -5,15 +5,15 @@ module Helpers
     extend Memoist
 
     def authenticate!
-      current_user || raise(AuthorizationError)
+      current_uid || raise(AuthorizationError)
     end
 
-    def current_user
-      key = 'api.v1.authenticated_uid' # JWT authentication provides user uid.
+    def current_uid
+      key = 'api.v1.authenticated_data' # JWT authentication provides user uid.
       return unless env.key?(key)
 
-      User.find_by(uid: env[key])
+      env[key][:uid]
     end
-    memoize :current_user
+    memoize :current_uid
   end
 end
diff --git a/app/api/api_v1/withdraw.rb b/app/api/api_v1/withdraw.rb
index 842ea43..0d5c5ed 100644
--- a/app/api/api_v1/withdraw.rb
+++ b/app/api/api_v1/withdraw.rb
@@ -22,7 +22,7 @@ class Withdraw < Grape::API
 
     post '/withdraws' do
       Peatio::ManagementAPIv1Client.new.create_withdraw \
-                                          uid:      env['api.v1.authenticated_uid'],
+                                          uid:      current_uid,
                                           currency: params[:currency],
                                           amount:   params[:amount],
                                           otp_code: params[:otp],
diff --git a/spec/api/v1/auth/jwt_authenticator_spec.rb b/spec/api/v1/auth/jwt_authenticator_spec.rb
index 0899cf8..63447bb 100644
--- a/spec/api/v1/auth/jwt_authenticator_spec.rb
+++ b/spec/api/v1/auth/jwt_authenticator_spec.rb
@@ -19,18 +19,14 @@
       headers:        { 'Authorization' => token }
   end
 
-  let :user do
-    create(:user, :level_3)
-  end
-
   let :payload do
-    { x: 'x', y: 'y', z: 'z', uid: user.uid }
+    { x: 'x', y: 'y', z: 'z', uid: 'O90Y88JDPQ7167' }
   end
 
   subject { APIv1::Auth::JWTAuthenticator.new(request.headers['Authorization']) }
 
   it 'should work in standard conditions' do
-    expect(subject.authenticate!).to eq user.uid
+    expect(subject.authenticate!).to eq payload.slice(:uid)
   end
 
   it 'should raise exception when uid is not provided' do
@@ -60,23 +56,11 @@
     end
   end
 
-  describe 'authentication options' do
-    it 'should return uid if return: :uid specified' do
-      expect(subject.authenticate!(return: :uid)).to eq payload[:uid]
-    end
-
-    it 'should return user if return: :user specified' do
-      create(:user)
-      payload[:uid] = user.uid
-      expect(subject.authenticate!(return: :user)).to eq user
-    end
-  end
-
   context 'valid issuer' do
     before { ENV['JWT_ISSUER'] = 'qux' }
     before { payload[:iss] = 'qux' }
     after  { ENV.delete('JWT_ISSUER') }
-    it('should validate issuer') { expect(subject.authenticate!).to eq user.uid }
+    it('should validate issuer') { expect(subject.authenticate!).to eq payload.slice(:uid) }
   end
 
   context 'invalid issuer' do
@@ -92,7 +76,7 @@
     before { ENV['JWT_AUDIENCE'] = 'foo,bar' }
     before { payload[:aud] = ['bar'] }
     after  { ENV.delete('JWT_AUDIENCE') }
-    it('should validate audience') { expect(subject.authenticate!).to eq user.uid }
+    it('should validate audience') { expect(subject.authenticate!).to eq payload.slice(:uid) }
   end
 
   context 'invalid audience' do
@@ -120,67 +104,6 @@
 
   context 'issued at before future' do
     before { payload[:iat] = 3.seconds.ago.to_i }
-    it('should allow JWT') { expect(subject.authenticate!).to eq user.uid }
-  end
-
-  describe 'on the fly registration' do
-    context 'token not issued by Barong' do
-      before { payload[:iss] = 'someone' }
-      it 'should not register user unless token is issued by Barong' do
-        expect { subject.authenticate! }.not_to change(User, :count)
-      end
-    end
-
-    context 'token issued by Barong' do
-      before { payload[:iss] = 'barong' }
-
-      it 'should require level to be present in payload' do
-        payload.merge!(state: 'pending', uid: Faker::Internet.password(14, 14), email: Faker::Internet.email)
-        expect { subject.authenticate! }.to raise_error(APIv1::AuthorizationError) { |e| expect(e.reason).to match /key not found: :level/ }
-      end
-
-      it 'should require state to be present in payload' do
-        payload.merge!(level: 1, uid: Faker::Internet.password(14, 14), email: Faker::Internet.email)
-        expect { subject.authenticate! }.to raise_error(APIv1::AuthorizationError) { |e| expect(e.reason).to match /key not found: :state/ }
-      end
-
-      it 'should require UID to be present in payload' do
-        payload.merge!(level: 1, state: 'disabled', email: Faker::Internet.email).delete(:uid)
-        expect { subject.authenticate! }.to raise_error(APIv1::AuthorizationError) { |e| expect(e.reason).to match /key not found: :uid/ }
-      end
-
-      it 'should require UID to be not blank' do
-        payload.merge!(level: 1, state: 'disabled', email: Faker::Internet.email, uid: ' ')
-        expect { subject.authenticate! }.to raise_error(APIv1::AuthorizationError) { |e| expect(e.reason).to match /UID is blank/ }
-      end
-
-      it 'should raise exception when email is invalid' do
-        payload[:email] = '@gmail.com'
-        expect { subject.authenticate! }.to raise_error(APIv1::AuthorizationError) { |e| expect(e.reason).to match /invalid/ }
-      end
-
-      it 'should register user' do
-        payload.merge!(email: 'guyfrombarong@email.com', uid: 'BARONG1234', state: 'active', level: 2)
-        expect { subject.authenticate! }.to change(User, :count).by(1)
-        record = User.last
-        expect(record.uid).to eq payload[:uid]
-        expect(record.level).to eq 2
-      end
-
-      it 'should update user if exists' do
-        user = create(:user, :level_1)
-        payload.merge!(email: Faker::Internet.email, uid: user.uid, state: 'blocked', level: 3)
-        expect { subject.authenticate! }.not_to change(User, :count)
-        user.reload
-        expect(user.uid).to eq payload[:uid]
-        expect(user.level).to eq 3
-      end
-
-      it 'should register new user and return instance' do
-        payload.merge!(email: 'guyfrombarong@email.com', uid: 'BARONG1234', state: '', level: 100)
-        expect(subject.authenticate!(return: :user)).to eq User.last
-        expect(User.last.level).to eq 100
-      end
-    end
+    it('should allow JWT') { expect(subject.authenticate!).to eq payload.slice(:uid) }
   end
 end
diff --git a/spec/api/v1/auth/middleware_spec.rb b/spec/api/v1/auth/middleware_spec.rb
index b91f577..bb83e74 100644
--- a/spec/api/v1/auth/middleware_spec.rb
+++ b/spec/api/v1/auth/middleware_spec.rb
@@ -9,15 +9,14 @@ class TestApp < Grape::API
 
     get '/' do
       authenticate!
-      current_user.uid
+      current_uid
     end
   end
 
   let(:app) { TestApp.new }
 
   context 'when using JWT authentication' do
-    let(:user) { create(:user, :level_3) }
-    let(:payload) { { x: 'x', y: 'y', z: 'z', uid: user.uid } }
+    let(:payload) { { x: 'x', y: 'y', z: 'z', uid: 'O90Y88JDPQ7167' } }
     let(:token) { jwt_build(payload) }
 
     it 'should deny access when token is not given' do
@@ -32,17 +31,10 @@ class TestApp < Grape::API
       expect(response.body).to eq '{"error":{"code":2001,"message":"Authorization failed"}}'
     end
 
-    it 'should deny access when member doesn\'t exist' do
-      payload[:uid] = 'BARONG1234'
-      api_get '/', token: token
-      expect(response.code).to eq '401'
-      expect(response.body).to eq '{"error":{"code":2001,"message":"Authorization failed"}}'
-    end
-
     it 'should allow access when valid token is given' do
       api_get '/', token: token
-      expect(response).to be_success
-      expect(response.body).to eq user.uid
+      expect(response).to be_successful
+      expect(response.body).to eq payload[:uid]
     end
   end
 
diff --git a/spec/api/v1/cors_spec.rb b/spec/api/v1/cors_spec.rb
index 9e3f36b..35f9b96 100644
--- a/spec/api/v1/cors_spec.rb
+++ b/spec/api/v1/cors_spec.rb
@@ -18,7 +18,7 @@ def check_cors(response)
   it 'sends CORS headers when requesting using OPTIONS' do
     reset! unless integration_session
     integration_session.send :process, 'OPTIONS', '/api/v1/withdraws'
-    expect(response).to be_success
+    expect(response).to be_successful
     check_cors(response)
   end