Postman simplifies API testing by allowing users to construct, send, and validate HTTP requests against REST endpoints. Consider a typical user management API that supports standard CRUD operations.

Core Endpoints

• GET /api/users – Retrieve all users
• POST /api/users – Create a new user
• GET /api/users/:id – Fetch a specific user
• PUT /api/users/:id – Update a user’s details
• DELETE /api/users/:id – Remove a user

Sending Requests

Retrieve All Users
Set the method to GET and enter the full URL (e.g., https://api.example.com/api/users). Click Send to view the JSON response, status code, and timing metrics.

Create a New User
Use the POST method with the same base URL. In the Body tab, select raw and choose JSON. Provide a payload like:

{
  "name": "Alice Smith",
  "email": "alice.smith@example.com"
}

After sending, verify the response includes the created user data and a 201 Created status.

Fetch a Specific User
Issue a GET request to https://api.example.com/api/users/5, replacing 5 with a valid ID. Confirm the returned object matches expected attributes.

Update a User
Select PUT, target the user’s endpoint (e.g., /api/users/5), and include an updated JSON body:

{
  "name": "Alice Johnson",
  "email": "alice.johnson@example.com"
}

A successful update typically returns 200 OK with the modified resource.

Delete a User
Send a DELETE request to the user’s endpoint. A 204 No Content or 200 OK usually indicates successful deletion.

Writing Automated Tests

In the Tests tab, add JavaScript assertions to validate behavior:

pm.test("Response status is 200", () => {
    pm.response.to.have.status(200);
});

pm.test("User email matches expected value", () => {
    const res = pm.response.json();
    pm.expect(res.email).to.eql("alice.johnson@example.com");
});

Test results appear in the Test Results panel after each request.

Organizing Workflows

Group related requests into a Collection via the Save button for reuse. Lveerage Environments to manage variables like {{base_url}}, enabling seamless switching between development, staging, and production setups without modifying individual requests.