Using mock server URL in Postman

Introduction

Using a mock server URL helps you test your API calls without needing the real server. It saves time and avoids errors when the real server is not ready.

When the real API server is still being built but you want to start testing.

When you want to simulate different responses to check how your app handles them.

When you want to test your API calls offline or without network dependency.

When you want to share a predictable API response with your team for collaboration.

When you want to speed up testing by avoiding slow or unreliable real servers.

Syntax

Postman

https://<mock-server-id>.mock.pstmn.io/<endpoint>

The mock server URL starts with https:// and includes a unique mock server ID.

Replace <mock-server-id> with your mock server's unique ID.

Replace <endpoint> with the API path you want to test.

Examples

This URL calls the mock server's /users endpoint.

Postman

https://12345abcde.mock.pstmn.io/users

This URL calls the mock server's /orders/123 endpoint to get order details.

Postman

https://67890fghij.mock.pstmn.io/orders/123

Sample Program

This is a simple GET request to a mock server URL for the /products endpoint. The mock server returns a fixed JSON response with product details.

Postman

GET https://12345abcde.mock.pstmn.io/products

Headers:
Content-Type: application/json

Expected Response:
{
  "id": "101",
  "name": "Coffee Mug",
  "price": 12.99
}

Important Notes

Always copy the mock server URL exactly from Postman to avoid errors.

You can customize mock responses in Postman to test different scenarios.

Mock servers do not execute real logic; they return predefined responses.

Summary

Mock server URLs let you test APIs without the real backend.

Use them when the real server is unavailable or for faster testing.

Mock URLs have a unique ID and endpoint path you must use correctly.

Practice

1. What is the main purpose of using a mock server URL in Postman?

easy

A. To speed up the internet connection

B. To store user data permanently

C. To test API requests without needing the real backend server

D. To create a live production environment

Solution

1. Step 1: Understand what a mock server does

   A mock server simulates API responses without calling the real backend.

2. Step 2: Identify the main use case

   This helps test APIs when the real server is unavailable or to speed up development.

3. Final Answer:

   To test API requests without needing the real backend server -> Option C

4. Quick Check:

   Mock server = test without real backend [OK]

Hint: Mock servers simulate APIs without real backend [OK]

Common Mistakes:

• Thinking mock servers speed up internet
• Confusing mock server with data storage
• Assuming mock server is for production

2. Which of the following is the correct way to use a mock server URL in Postman?

easy

A. Replace the real API base URL with the mock server URL including the unique ID

B. Add the mock server URL as a query parameter to the real URL

C. Use the mock server URL only in the request headers

D. Append the mock server URL after the response body

Solution

1. Step 1: Understand mock server URL usage

   You replace the real API base URL with the mock server URL that includes the unique mock ID.

2. Step 2: Check other options

   Adding as query parameter, headers, or after response body is incorrect usage.

3. Final Answer:

   Replace the real API base URL with the mock server URL including the unique ID -> Option A

4. Quick Check:

   Mock URL replaces base URL [OK]

Hint: Mock URL replaces real API base URL [OK]

Common Mistakes:

• Adding mock URL as query parameter
• Using mock URL only in headers
• Appending mock URL after response

3. Given the mock server URL https://mockserver.com/12345/api/users, what will happen if you send a GET request to this URL in Postman?

medium

A. You will get a mocked response defined in the mock server for the /api/users endpoint

B. The request will fail because mock servers do not support GET requests

C. You will get a real response from the live backend server

D. Postman will ignore the mock server URL and use the environment variable URL

Solution

1. Step 1: Understand mock server behavior

   Mock servers return predefined responses for requests sent to their URLs.

2. Step 2: Analyze the given URL and request

   Sending GET to the mock URL returns the mocked response for /api/users.

3. Final Answer:

   You will get a mocked response defined in the mock server for the /api/users endpoint -> Option A

4. Quick Check:

   GET to mock URL returns mock response [OK]

Hint: GET to mock URL returns predefined mock response [OK]

Common Mistakes:

• Thinking mock servers reject GET requests
• Expecting real backend response
• Assuming environment variables override mock URL

4. You set the mock server URL incorrectly by missing the unique ID part, like https://mockserver.com/api/users. What issue will you face?

medium

A. The request will succeed and return the correct mock response

B. Postman will fail to route the request to the mock server and return an error

C. Postman will automatically add the missing unique ID

D. The request will be sent to the real backend server instead

Solution

1. Step 1: Identify the importance of unique ID in mock URL

   The unique ID is required to route requests to the correct mock server instance.

2. Step 2: Consequence of missing unique ID

   Without it, Postman cannot find the mock server and returns an error.

3. Final Answer:

   Postman will fail to route the request to the mock server and return an error -> Option B

4. Quick Check:

   Missing mock ID causes routing error [OK]

Hint: Always include unique ID in mock URL [OK]

Common Mistakes:

• Assuming Postman auto-fixes missing ID
• Expecting fallback to real backend
• Thinking request will succeed without ID

5. You want to test an API endpoint /products using a Postman mock server. Your mock server URL is https://mockserver.com/abcde. Which is the correct full URL to use in your request to get the mocked /products response?

hard

A. https://mockserver.com/api/abcde/products

B. https://mockserver.com/products/abcde

C. https://mockserver.com/abcde/api/products

D. https://mockserver.com/abcde/products

Solution

1. Step 1: Understand mock server URL structure

   The mock server URL includes the unique ID, followed by the API endpoint path.

2. Step 2: Construct the correct full URL

   Append the endpoint /products directly after the unique ID in the URL.

3. Final Answer:

   https://mockserver.com/abcde/products -> Option D

4. Quick Check:

   Mock URL + endpoint path = full request URL [OK]

Hint: Append endpoint path after mock server URL with ID [OK]

Common Mistakes:

• Placing unique ID after endpoint path
• Adding extra /api/ segment incorrectly
• Mixing order of ID and endpoint