diff --git a/app/adapters/abstract_adapter.rb b/app/adapters/abstract_adapter.rb
index b851f6c8..628f7e8e 100644
--- a/app/adapters/abstract_adapter.rb
+++ b/app/adapters/abstract_adapter.rb
@@ -203,7 +203,7 @@ def oauth_client
 
     def fetch_oidc_discovery
       response = http_client.get(well_known_url)
-      config = AbstractAdapter.parse_response(response)
+      config = response.ok? && AbstractAdapter.parse_response(response)
 
       case config
       when ->(obj) { obj.respond_to?(:[]) } then config
diff --git a/app/adapters/rest_adapter.rb b/app/adapters/rest_adapter.rb
index 22ac20e2..eacfbdfb 100644
--- a/app/adapters/rest_adapter.rb
+++ b/app/adapters/rest_adapter.rb
@@ -31,6 +31,12 @@ def test
     parse http_client.get(oidc.well_known_url, header: headers)
   end
 
+  def authentication
+    super
+  rescue OIDC::AuthenticationError
+    nil
+  end
+
   # The Client entity. Mapping the OpenID Connect Client Metadata representation.
   # https://tools.ietf.org/html/rfc7591#section-2
   class Client
diff --git a/examples/rest-api/.gitignore b/examples/rest-api/.gitignore
new file mode 100644
index 00000000..79f33806
--- /dev/null
+++ b/examples/rest-api/.gitignore
@@ -0,0 +1 @@
+clients.yml
diff --git a/examples/rest-api/Gemfile b/examples/rest-api/Gemfile
new file mode 100644
index 00000000..c7a4cfbb
--- /dev/null
+++ b/examples/rest-api/Gemfile
@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+source 'https://rubygems.org'
+
+gem 'sinatra'
+
+gem 'pry-byebug'
diff --git a/examples/rest-api/Gemfile.lock b/examples/rest-api/Gemfile.lock
new file mode 100644
index 00000000..62eff627
--- /dev/null
+++ b/examples/rest-api/Gemfile.lock
@@ -0,0 +1,32 @@
+GEM
+  remote: https://rubygems.org/
+  specs:
+    byebug (11.0.1)
+    coderay (1.1.2)
+    method_source (0.9.2)
+    mustermann (1.0.3)
+    pry (0.12.2)
+      coderay (~> 1.1.0)
+      method_source (~> 0.9.0)
+    pry-byebug (3.7.0)
+      byebug (~> 11.0)
+      pry (~> 0.10)
+    rack (2.0.7)
+    rack-protection (2.0.5)
+      rack
+    sinatra (2.0.5)
+      mustermann (~> 1.0)
+      rack (~> 2.0)
+      rack-protection (= 2.0.5)
+      tilt (~> 2.0)
+    tilt (2.0.9)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  pry-byebug
+  sinatra
+
+BUNDLED WITH
+   2.0.1
diff --git a/examples/rest-api/README.md b/examples/rest-api/README.md
new file mode 100644
index 00000000..a85f2fe9
--- /dev/null
+++ b/examples/rest-api/README.md
@@ -0,0 +1,58 @@
+# Zync REST API example
+
+This example project implements Zync's REST API protocol to synchronize OAuth2 clients.
+
+## Prerequisites
+
+Given 3scale API is configured to use:
+  * OpenID Connect as the Authentication,
+  * "REST API" as a OpenID Connect Issuer Type and
+  * "http://id:secret@example.com/api" as OpenID Connect Issuer.
+
+When a 3scale application is created/updated/deleted zync will try to replay that change to "http://example.com/api".
+
+## Creating, updating and deleting Clients
+
+Zync will make following requests to create/update/delete clients:
+
+* `PUT /clients/:client_id` (create, update)
+* `DELETE /clients/:client_id` (delete)
+
+All endpoints must reply 2xx status code. Otherwise the request will be retried.
+
+### Payload
+
+The request payload in case of create and update is `application/json`:
+
+```json
+{
+  "client_id": "ee305610",
+  "client_secret": "ac0e42db426b4377096c6590e2b06aed",
+  "client_name": "oidc-app",
+  "redirect_uris": ["http://example.com"],
+  "grant_types": ["client_credentials", "password"]
+}
+```
+
+The request to delete a client has no payload.
+
+## Using OAuth2 authentication
+
+Zync will make GET request to `/.well-known/openid-configuration` endpoint and expect an `application/json` response.
+The response payload should contain following: 
+
+```json
+{
+  "token_endpoint": "http://idp.example.com/auth/realm/token"
+}
+```
+
+Zync will use that `token_endpoint` URL to exchange the client_id and client_secret provided in the OpenID Connect Issuer URL 
+for an access token using the OAuth2 protocol.
+
+If the API responds with not successful response, Zync will fallback to HTTP Basic/Digest authentication using provided credentials.
+ 
+## References
+
+* OpenAPI Specification document [openapi.yml](openapi.yml)
+* Sinatra application [app.rb](app.rb) 
diff --git a/examples/rest-api/app.rb b/examples/rest-api/app.rb
new file mode 100644
index 00000000..8299d005
--- /dev/null
+++ b/examples/rest-api/app.rb
@@ -0,0 +1,54 @@
+# frozen_string_literal: true
+
+require 'sinatra'
+require 'json'
+require 'yaml/store'
+
+$store = YAML::Store.new('clients.yml')
+$basic_auth =  Rack::Auth::Basic.new(->(_) { [] }, 'REST API') do |username, password|
+  username.length > 0 && password.length > 0
+end
+
+def json(object)
+  headers 'Content-Type' => 'application/json'
+  body JSON(object)
+end
+
+get '/.well-known/openid-configuration' do
+  # point zync where to exchange the OAuth2 access token
+  json({ token_endpoint: 'https://example.com/auth/realms/master/protocol/openid-connect/token' })
+end
+
+put '/clients/:client_id' do |client_id|
+  # {"client_id"=>"ee305610",
+  #  "client_secret"=>"ac0e42db426b4377096c6590e2b06aed",
+  #  "client_name"=>"oidc-app",
+  #  "redirect_uris"=>["http://example.com"],
+  #  "grant_types"=>["client_credentials", "password"]}
+  client = JSON.parse(request.body.read)
+
+  # store the client
+  $store.transaction do
+    $store[client_id] = client
+  end
+
+  json(client)
+end
+
+delete '/clients/:client_id' do |client_id|
+  # Request HTTP Basic authentication
+  if (status, headers, body = $basic_auth.call(env))
+    self.headers headers
+    error status, body
+  end
+
+  client = nil
+
+  # remove the client
+  $store.transaction do
+    client = $store[client_id]
+    $store.delete(client_id)
+  end
+
+  json(client)
+end
diff --git a/examples/rest-api/config.ru b/examples/rest-api/config.ru
new file mode 100644
index 00000000..221725af
--- /dev/null
+++ b/examples/rest-api/config.ru
@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+require_relative 'app'
+
+run Sinatra::Application
diff --git a/examples/rest-api/openapi.yml b/examples/rest-api/openapi.yml
new file mode 100644
index 00000000..40f1c3b1
--- /dev/null
+++ b/examples/rest-api/openapi.yml
@@ -0,0 +1,146 @@
+---
+openapi: 3.0.2
+info:
+  title: Zync REST API
+  version: 1.0.0
+paths:
+  /clients/{clientId}:
+    get:
+      summary: Get a Client
+      operationId: readClient
+      parameters:
+      - name: clientId
+        in: path
+        description: client_id
+        required: true
+        schema:
+          type: string
+      responses:
+        200:
+          description: Client resource was found.
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Client'
+      security:
+      - OIDC: []
+        Basic: []
+        Digest: []
+    put:
+      summary: Create or update the Client
+      operationId: saveClient
+      requestBody:
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/Client'
+            examples:
+              Client:
+                value:
+                  client_id: foo-bar
+                  client_secret: some-secret
+        required: true
+      responses:
+        200:
+          description: When the Client was updated.
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Client'
+        201:
+          description: When the Client was created on the IDP.
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Client'
+    delete:
+      summary: Delete the Client
+      operationId: deleteClient
+      responses:
+        200:
+          description: When the client was deleted.
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Client'
+        204:
+          description: When the Client was already gone from the IDP.
+          content:
+            application/json: {}
+    parameters:
+    - name: clientId
+      in: path
+      required: true
+  /.well-known/openid-configuration:
+    get:
+      responses:
+        200:
+          description: Enable OAuth2.0 authentication by responding with a token endpoint
+            of an IDP.
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/OIDC'
+              examples:
+                Enable OAuth2.0 authentication:
+                  value:
+                    token_endpoint: https://idp.example.com/auth/realms/myrealm
+      security:
+      - {}
+components:
+  schemas:
+    Client:
+      title: Root Type for Client
+      description: A Client representation.
+      required: []
+      type: object
+      properties:
+        client_id:
+          type: string
+        client_secret:
+          type: string
+        client_name:
+          type: string
+        redirect_uris:
+          description: A list of allowed redirect uris.
+          type: array
+          items:
+            type: string
+        grant_types:
+          description: A list of allowed grant types.
+          type: array
+          items:
+            type: string
+      example: |-
+        {
+            "client_id": "foo-bar",
+            "client_secret": "some-secret"
+        }
+    OIDC:
+      title: Root Type for OIDC
+      description: OpenID Connect Configuration to define where to get access token.
+      type: object
+      properties:
+        token_endpoint:
+          type: string
+      example: |-
+        {
+            "token_endpoint": "https://idp.example.com/auth/realms/myrealm"
+        }
+  securitySchemes:
+    OIDC:
+      type: openIdConnect
+      description: |-
+        Use OpenID Connect for authentication.
+        Zync will try to access `/.well-known/openid-configuration` and use "token_endpoint" property from the JSON response.
+        Then it will exchange its' credentials for an access token and will use that access token to access this API.
+    Basic:
+      type: http
+      description: Zync will try to send provided credentials as HTTP Basic authentication
+        in case it gets a 401 response with proper WWW-Authenticate header.
+      scheme: basic
+    Digest:
+      type: http
+      description: Zync will try to send provided credentials as HTTP Basic authentication
+        in case it gets a 401 response with proper WWW-Authenticate header.
+      scheme: digest
diff --git a/test/adapters/abstract_adapter_test.rb b/test/adapters/abstract_adapter_test.rb
index 66b8e7db..e00332a0 100644
--- a/test/adapters/abstract_adapter_test.rb
+++ b/test/adapters/abstract_adapter_test.rb
@@ -29,4 +29,13 @@ class AbstractAdapterTest < ActiveSupport::TestCase
       assert_kind_of subject, subject.new('http://id:secret@example.com')
     end
   end
+
+  test 'oidc discovery' do
+    stub_request(:get, "https://example.com/.well-known/openid-configuration").
+      to_return(status: 404, body: '', headers: {})
+
+    assert_raises AbstractAdapter::OIDC::AuthenticationError do
+      assert_nil subject.new('https://example.com').authentication
+    end
+  end
 end
diff --git a/test/adapters/rest_adapter_test.rb b/test/adapters/rest_adapter_test.rb
new file mode 100644
index 00000000..fa91acfc
--- /dev/null
+++ b/test/adapters/rest_adapter_test.rb
@@ -0,0 +1,47 @@
+# frozen_string_literal: true
+require 'test_helper'
+
+class RESTAdapterTest < ActiveSupport::TestCase
+  class_attribute :subject, default: RESTAdapter
+
+  test 'oidc discovery' do
+    stub_request(:get, "https://example.com/.well-known/openid-configuration").
+      to_return(status: 404, body: '', headers: {})
+
+    assert_nil subject.new('https://example.com').authentication
+  end
+
+  test 'create client without auth' do
+    client = RESTAdapter::Client.new(id: 'foo')
+
+    stub_request(:get, "https://example.com/.well-known/openid-configuration").
+      to_return(status: 404, body: '', headers: {})
+
+    stub_request(:put, "https://example.com/clients/foo").
+      with(
+        body: client.to_json,
+        headers: { 'Content-Type'=>'application/json' }).
+      to_return(status: 200, body: { status: 'ok' }.to_json, headers: { 'Content-Type' => 'application/json' })
+
+    assert subject.new('https://example.com').create_client(client)
+  end
+
+  test 'create client with basic auth' do
+    client = RESTAdapter::Client.new(id: 'foo')
+    adapter = subject.new('https://user:pass@example.com')
+    # WebMock does not support request retries on 401 status
+    adapter.send(:http_client).force_basic_auth = true
+
+    stub_request(:get, "https://example.com/.well-known/openid-configuration").
+      to_return(status: 404, body: '', headers: {})
+
+    stub_request(:put, 'https://example.com/clients/foo').
+      with(
+        basic_auth: %w[user pass],
+        body: client.to_json,
+        headers: { 'Content-Type'=>'application/json' }).
+      to_return(status: 200, body: { status: 'ok' }.to_json, headers: { 'Content-Type' => 'application/json' })
+
+    assert adapter.create_client(client)
+  end
+end