Load testing basics (Postman)

Introduction

Load testing helps check if a website or app can handle many users at once without slowing down or crashing.

Before launching a new website to make sure it can handle visitors.

When adding new features that might affect performance.

To find the maximum number of users your app can support.

After fixing bugs to confirm the app still works well under stress.

To compare performance before and after updates.

Syntax

Postman

1. Open Postman.
2. Create or select a request.
3. Click on the "Runner" button.
4. Set the number of iterations (how many times to run).
5. Use "Delay" to add wait time between requests.
6. Click "Run" to start the load test.

Postman Runner simulates multiple requests but is limited for heavy load testing.

For more advanced load testing, use Postman with external tools like Newman and a load generator.

Examples

This runs the request 50 times with 100 milliseconds pause between each.

Postman

Runner settings:
Iterations: 50
Delay: 100 ms
Run the test

This runs 100 requests as fast as possible to simulate high load.

Postman

Runner settings:
Iterations: 100
Delay: 0 ms
Run the test

Sample Program

This example tests if the sample API can handle 10 quick requests in a row.

Postman

GET https://jsonplaceholder.typicode.com/posts/1

// Steps to run load test in Postman Runner:
// 1. Open this GET request in Postman.
// 2. Click Runner.
// 3. Set Iterations to 10.
// 4. Set Delay to 50 ms.
// 5. Click Run.

// Expected result:
// All 10 requests complete successfully with status 200.
// Response times are shown in Runner summary.

Important Notes

Postman load testing is good for small to medium tests but not for very high traffic.

Always monitor server health during load tests to avoid crashes.

Use environment variables in Postman to test different data during load tests.

Summary

Load testing checks how many users your app can handle at once.

Postman Runner can simulate multiple requests to do basic load testing.

For heavy load tests, combine Postman with other tools like Newman or dedicated load testers.

Practice

1. What is the main purpose of load testing in Postman?

easy

A. To check how many users the app can handle at the same time

B. To find syntax errors in API requests

C. To test the UI responsiveness of the app

D. To verify database schema correctness

Solution

1. Step 1: Understand load testing goal

   Load testing is about simulating many users to see how the app performs under stress.

2. Step 2: Match with Postman usage

   Postman can send multiple requests to simulate users, so it helps check app capacity.

3. Final Answer:

   To check how many users the app can handle at the same time -> Option A

4. Quick Check:

   Load testing = user capacity check [OK]

Hint: Load testing = many users at once [OK]

Common Mistakes:

• Confusing load testing with syntax checking
• Thinking load testing checks UI only
• Mixing load testing with database tests

2. Which Postman feature allows you to run multiple requests repeatedly for load testing?

easy

A. Postman Runner

B. Postman Console

C. Postman Monitor

D. Postman Collection Editor

Solution

1. Step 1: Identify Postman features for running requests

   Postman Runner lets you run a collection of requests multiple times.

2. Step 2: Match feature to load testing

   Running requests repeatedly simulates load, so Runner is the correct tool.

3. Final Answer:

   Postman Runner -> Option A

4. Quick Check:

   Repeated runs = Postman Runner [OK]

Hint: Use Runner to repeat requests [OK]

Common Mistakes:

• Choosing Console which is for debugging
• Confusing Monitor with scheduled tests
• Thinking Collection Editor runs requests

3. Consider this Postman Runner setup: you run 100 iterations with 10 requests each. How many total requests are sent?

medium

A. 100

B. 10

C. 1000

D. 110

Solution

1. Step 1: Understand iterations and requests per iteration

   Each iteration runs 10 requests, and there are 100 iterations total.

2. Step 2: Calculate total requests

   Total requests = 100 iterations * 10 requests = 1000 requests.

3. Final Answer:

   1000 -> Option C

4. Quick Check:

   100 x 10 = 1000 [OK]

Hint: Multiply iterations by requests per iteration [OK]

Common Mistakes:

• Adding instead of multiplying
• Confusing iterations with requests
• Ignoring requests per iteration

4. You tried to run a load test in Postman Runner but only one request was sent repeatedly instead of the whole collection. What is the likely mistake?

medium

A. You forgot to save the collection

B. You selected a single request instead of the full collection

C. You used Monitor instead of Runner

D. You set iterations to 1

Solution

1. Step 1: Analyze the problem

   Only one request runs repeatedly, not the whole collection.

2. Step 2: Identify cause

   This happens if you run a single request in Runner instead of the entire collection.

3. Final Answer:

   You selected a single request instead of the full collection -> Option B

4. Quick Check:

   Single request run = wrong selection [OK]

Hint: Always select full collection for load test [OK]

Common Mistakes:

• Thinking iterations = 1 causes this
• Confusing Monitor with Runner
• Assuming saving fixes request selection

5. You want to perform a heavy load test beyond Postman's Runner limits. Which approach is best?

hard

A. Increase iterations in Postman Runner to 10,000

B. Use Postman Console to debug requests

C. Run Postman Monitor continuously for 24 hours

D. Use Newman in combination with a load testing tool like Apache JMeter

Solution

1. Step 1: Understand Postman Runner limits

   Postman Runner is good for basic load but not for very heavy or distributed load testing.

2. Step 2: Identify best heavy load testing method

   Newman can run collections from command line and can be integrated with tools like JMeter for heavy load.

3. Final Answer:

   Use Newman in combination with a load testing tool like Apache JMeter -> Option D

4. Quick Check:

   Heavy load = Newman + load tool [OK]

Hint: Combine Newman with load tools for heavy tests [OK]

Common Mistakes:

• Trying to increase Runner iterations too high
• Using Monitor for load testing
• Using Console for load testing