User Authentication

Learn how to guide users through the login process, enabling them to access Techniek Nederland’s web services. Detailed instructions will be provided on utilizing the OAuth protocol to authenticate users via the Techniek Nederland IDP.

Basic Concept of the Login Process:

  1. User opens your Application and needs to log in.

  2. Your Application redirects the User to the Identity Provider (IDP), providing information to the IDP about your application, the actions you want to perform on behalf of the user, and where the IDP should redirect the user within your application after successful login.

  3. The User logs in to the IDP using their credentials.

  4. The IDP informs the User about the actions your Application wants to perform on their behalf and requests their permission.

  5. The IDP redirects the User back to the specified address of your Application, along with a unique code that can be used to perform actions on behalf of this user.

  6. The following sections will provide further details on this process, including example HTTP requests. We recommend utilizing existing OAuth implementations to handle the authentication flow, which would eliminate the need for manually constructing raw HTTP requests.

Step 1: Register Your Application with Techniek Nederland

To use the IDP, your application needs to have identification credentials registered with Techniek Nederland. In this tutorial, we assume your application is unable to securely store secrets. Examples include web browser-based applications (JavaScript applications) or applications installed on the user’s computer. Since these applications are visible to the user, they cannot securely store secrets. Therefore, we will only use a client_id in combination with PKCE (Proof Key for Code Exchange), rather than a client_id and client_secret.

To register your application, please send an email to Peter Zwakhals with the following information:

  • Application name

  • Why your going to use the IDP

  • The redirect_url - the address(es) to which the user should be redirected after a successful login attempt

When making the request, ensure that you provide the complete URL, not just the domain. For example, ‘’. Also, consider providing any development addresses you would like to include, such as ‘http://localhost:8000/oauth-callback/’ and ‘’.

Step 2: Configure Your Application

In this step, we will describe the information you receive from Techniek Nederland and demonstrate how to test it using Postman.

After registering your application with Techniek Nederland, you will receive a client_id. This is a unique identifier that allows the IDP to identify your application. The client_id should be included in your application’s code and in your requests to the IDP. It can be seen by the user and is therefore considered public.

You will need the following information:






To be requested


Not applicable for client applications


Authorization code (make sure to use PKCE)


openid, profile, FGO, FGOWS


The meaning of these terms is beyond the scope of this documentation. We kindly refer to the documentation of the OAuth library you choose, or alternatively, resources such as Auth0, which provide clear explanations of these terms.

With this information, you can now configure your application. In this tutorial, we will describe how you can configure Postman.

  1. Open Postman.

  2. Choose ‘New’ > ‘Workspace’.

  3. Name it ‘Techniek Nederland’.

  4. Click ‘New’ > ‘Collection’ and name it ‘Identity Service Provider’.

  5. Open ‘Identity Service Provider’ in the left side menu.

  6. You will now see the content, and the ‘Authorization’ tab is active.

  7. The ‘Type’ is currently set to “No Auth”. Change it to ‘OAuth2’.

  8. Go to ‘Configure new token’ and select ‘edit’ if necessary.

  9. Set the Token Name to ‘Techniek Nederland IDP’ (you can choose any name you prefer).

  10. Fill in the configuration details (refer to the screenshot as well).

  11. Click ‘Get New Access Token’.

Continue to Step 3 for further instructions.

Configuration in Postman

Please note that the provided screenshot is for reference only, and the actual configuration may differ based on your specific OAuth implementation and Postman version.

Step 3: Authorize your application to act on the user’s behalf

In the authorization step, you will authorize your application to perform actions on behalf of the user. It’s important to note that this step is about authorizing your application, not the user authorizing themselves. To authorize, you will redirect the user to the Identity Service Provider (IDP) and request the IDP to grant access to specific data and actions (scopes) on behalf of the user. If the user grants permission, your application will receive a temporary authorization code (access_code), which will be used in the next step to request access.

Generating the PKCE code is beyond the scope of this tutorial.

When using a library (or Postman), the user is redirected to the IDP for authorization. If you choose to implement the call yourself, it would look like the following (note that this call is not performed in the background, you actually redirect the user to this address):


Authorize your application to access resources on behalf of a user.

Query Parameters
  • response_type – The response type. Set to “code”.

  • client_id – Your client ID.

  • scope – The requested scope (eg. “openid, profile, FGO, FGOWS”).

  • redirect_uri – The redirect URI after successful authorization.

  • code_challenge – The code challenge generated using PKCE.

  • code_challenge_method – The code challenge method. Set to “S256”.

GET /o/authorize/?response_type=code&client_id=YOUR_CLIENT_ID&scope=openid%2C%20profile%2C%20FGO%2C%20FGOWS& HTTP/1.1
Accept: application/json

A web browser will open the login screen of Techniek Nederland’s IDP. Log in with your Techniek Nederland account. During the first login, you will be asked to grant permission for your application to log in on your behalf as the logged-in user. Once the user grants permission, they will be redirected to the address specified in the redirect_uri parameter. This request will include the code parameter, which you will use in step 4 to retrieve the access token.


The redirect URI of your own application. For demonstration purposes we use Postman, but in your application this will definetly be something else.

Query Parameters
  • code – The authorization code received from the authorization server which you need in the next step

GET /oauth2/callback?code=ABCDEFGabcdefg0123456789 HTTP/1.1

Step 4: Obtaining an access token

With the temporary authorization code from setp 3, you can now request an access token and related information. The access token is ultimately the means by which you can retrieve data on behalf of the user. For example, you can use it to request information about the user from the IDP or access other web services that the user has granted you permission to.

It’s important to note that the access code is also temporary. For security reasons, the access token expires after a certain period of time. This is crucial because the access token is shared with external entities, such as other web services. That’s why you also receive a refresh token. You should only share this token with the IDP and only share it once, when requesting a new set of access tokens, refresh tokens, etc. The refresh token can only be used once, and after that, you will receive a new one. Finally, you also receive an id token (when using the openid scope). This token contains encoded user information, but how to decode it is beyond the scope of this tutorial to cover its details.

How the code_verifier was generated is beyond the scope of this tutorial.

In step 2 your hit the ‘Get New Access Token’ in Postman. Step 3 and step 4 are performed automatically after the user gives permission. You will now see the ‘token details’ provided by the IDP. If you want to make the http call manually, you can use the following HTTP request:


Request access token

Request Headers
Query Parameters
  • grant_type – The grant type. Set to “authorization_code”.

  • code – The authorization code received in the previous step.

  • code_verifier – The code verifier (for PKCE).

POST /o/token/ HTTP/1.1
Content-Type: application/x-www-form-urlencoded


Example response

HTTP/1.1 200 OK
Content-Type: application/json

  "access_token": "ABCDEFGabcdefg0123456789",
  "expires_in": 36000,
  "token_type": "Bearer",
  "scope": "openid profile",
  "refresh_token": "ABCDEFGabcdefg0123456789",
  "id_token": "eyJ0...---"

Your application is now authorized to make requests on behalf of the user. You’ve reach the end of this tutorial and can now continue to the User Data Retrieval tutorial where we will explain how to use your token to obtain user info.