Practice Exercises

Reading about Postman is not the same as using Postman. This lesson is all hands-on. Open Postman and complete every exercise below. No shortcuts — the muscle memory matters.

Exercise 1: Build a Complete Collection

Create a collection called "TesterRank — API Practice" with the following structure and requests. Save every request with a descriptive name.

TesterRank — API Practice/
  Variables:
    baseUrl = https://jsonplaceholder.typicode.com

  Posts/
    List All Posts          GET {{baseUrl}}/posts
    Get Single Post         GET {{baseUrl}}/posts/:id          (id = 1)
    Get Posts by User       GET {{baseUrl}}/posts?userId=1
    Create New Post         POST {{baseUrl}}/posts             (with JSON body)
    Full Update Post        PUT {{baseUrl}}/posts/:id          (id = 1, full body)
    Partial Update Post     PATCH {{baseUrl}}/posts/:id        (id = 1, title only)
    Delete Post             DELETE {{baseUrl}}/posts/:id       (id = 1)

  Users/
    List All Users          GET {{baseUrl}}/users
    Get Single User         GET {{baseUrl}}/users/:id          (id = 3)
    Create New User         POST {{baseUrl}}/users             (with JSON body)

  Comments/
    Get Comments for Post   GET {{baseUrl}}/posts/:postId/comments    (postId = 1)
    Get Comments by Email   GET {{baseUrl}}/comments?email=Eliseo@gardner.biz

Exercise 2: Complete CRUD Cycle

Exercise 3: Header Investigation

Send GET {{baseUrl}}/posts/1 and answer these questions by inspecting the response:

1. What is the Content-Type response header value?
2. What is the response time in milliseconds?
3. How many response headers are there in total?
4. Is there a Cache-Control header? What's its value?
5. Is there an X-Powered-By header? (If yes, that's a security concern)
6. How many fields does the response body have?
7. What data type is the "userId" field — string or number?

Exercise 4: Query Parameter Testing

Using the Params tab (not typing in the URL), test these queries:

1. GET /posts?userId=1 — How many posts does user 1 have?
2. GET /posts?userId=1&_limit=3 — Does it limit to 3 results?
3. GET /comments?postId=1 — How many comments on post 1?
4. GET /todos?userId=1&completed=true — How many completed todos?
5. GET /todos?userId=999 — What happens with a non-existent user?
6. Toggle the userId param OFF (uncheck it) and send again. What changes?

Exercise 5: Inspect Live APIs on Banking Portal