Understanding Callback URLs in Postman
Tags: postman
Published: 2024-07-12 10:11:11

Web applications and APIs often require bi-directional communication, especially when actions initiated by users involve complex or time-consuming processes. Callback URLs are essential in these instances, serving as predetermined addresses that facilitate the return of information to the initiating application upon task completion.

### Detailed Workflow of Callback URLs

#### **Step 1: Triggering a Process**

Consider a scenario where you need to upload a sizeable video to a web application for processing. The application packages this video alongside necessary instructions and sends it to the server for processing.

#### **Step 2: Handling Processing Delays**

Video processing can be resource-intensive, requiring considerable time. It's impractical for the server to maintain an open connection throughout this period waiting for the application to request a status update.

#### **Step 3: Establishing a Callback URL**

To manage this, the user specifies a callback URL — a designated endpoint within the application. This URL directs the server on where to send the notifications upon completing the video processing.

#### **Step 4: Notification of Completion**

Upon completion, the server dispatches the outcome of the processing—be it a success or a failure along with any relevant processing details — back to the application via the established callback URL.

#### **Step 5: Automatic Update Reception**

The application does not need to continuously poll for status updates. It receives them directly and automatically via the callback URL, ensuring the user is promptly informed about the task's outcome.

## Postman's Implementation of Callback URLs in OAuth 2.0

[Postman](https://apidog.com/blog/what-is-postman/) simplifies the OAuth 2.0 authorization process through its adept use of callback URLs. OAuth 2.0 is a security framework that enables applications to access resources from another application, like a Google account, without sharing user credentials.

### Essential Steps in OAuth 2.0 Involving Callback URLs

1. **Initial User Authorization**: An application directs the user to an authentication page (e.g., Google's login page) where they can log in securely.
2. **Permission Granting**: Post-login, the user permits the app to access specific details from their account.
3. **Receiving Authorization Code**: The authentication server sends an authorization code to the application’s preset callback URL.

### Postman’s Efficient Authorization Process

#### Configuring Callback URL in Postman

Inside Postman, the setup includes specifying either a local callback URL provided by Postman for internal testing or a public URL for more realistic, production-mimicking environments.

#### Capturing the Authorization Code

The authorization code returned to Postman’s callback URL eliminates the need for redirecting the user further. Postman uses this code directly to request access tokens from the authorization server.

#### Token Retrieval Without Redirection

This streamlined process negates user redirection to external applications, as Postman manages the entire flow internally. This feature is crucial for testing API interactions efficiently.

## Advantages of Using Callback URLs in Postman

- **Simplicity**: Postman manages the entire authentication flow internally.
- **Speed**: Reduces setup time, accelerating access to necessary tokens.
- **Adaptability**: Facilitates straightforward testing of different OAuth 2.0 scenarios without complex configurations.

## Setting Up a Callback URL in Postman for OAuth 2.0 Authorization

### Steps to Configure OAuth 2.0

Access the Authorization tab within your selected Postman request or collection to start this setup.

![postman authorization tab](https://assets.apidog.com/blog/2024/07/postman-authorization-tab.png)

### Selection of OAuth 2.0

Choose `OAuth 2.0` as the authorization type to view relevant configuration settings.

![postman select oauth 2.0](https://assets.apidog.com/blog/2024/07/postman-authorization-select-oauth-2.png)

### Inputting the Callback URL

Enter the desired callback URL in the specified section. Options include using Postman’s local testing URL or a registered public URL for broader testing.

![postman insert callback url](https://assets.apidog.com/blog/2024/07/postman-fill-in-callback-url.png)

### Applying the Configuration Changes

Ensure to save all modifications to deploy them in API testing.

![postman save api changes](https://assets.apidog.com/blog/2024/07/postman-save-api-changes.png)

## Using Callback URLs in Apidog for OAuth 2.0

[Apidog](https://www.apidog.com/?utm_source=&utm_medium=blogger&utm_campaign=test1) offers a similar configuration process with a user-friendly interface, simplifying the authentication setup for API testing.

### OAuth 2.0 Configuration in Apidog

![apidog select oauth 2.0 authentication](https://assets.apidog.com/blog/2024/07/apidog-auth-select-oauth-2.0.png)

Within Apidog, navigate to the authorization settings of your API or request, select `OAuth 2.0`, and input your callback URL as needed.

## Conclusion

Utilizing callback URLs in tools like Postman and Apidog revolutionizes the efficiency of setting up and testing OAuth 2.0 authorization workflows. By automating code interception and token retrieval, these tools significantly reduce the complexity associated with API testing, enhancing productivity and focus on core development tasks.