API Testing Tutorial: Free Manual and Automation Course

API Testing Tutorial: Free Manual and Automation Course

Learn API testing from zero to job-ready, completely free. This course takes you from “what is an API?” to manual testing with Postman and SoapUI, automation with Playwright and TypeScript, five real portfolio projects, using AI to test faster, and interview preparation. Every lesson uses a live practice API hosted on SQA Tools, so you test real endpoints instead of just reading about them.

Start Lesson 1: What Is API Testing? →Open the Practice API

What is API testing?API testing is software testing that sends requests directly to an application’s API and verifies the responses: status codes, data, schema, headers, security and performance, without going through the user interface. It’s faster and more stable than UI testing and finds bugs earlier, which makes it one of the most in-demand QA skills in 2026.
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What You Will Learn

API and HTTP fundamentals

Request and response, types of APIs, REST vs SOAP vs GraphQL, HTTP methods, status codes, headers, JSON and JSON Schema.

Manual API testing

Write API test cases, Postman collections and scripts, Newman, cURL, SoapUI for SOAP and REST, Swagger/OpenAPI.

Security and authentication

Basic auth, API keys, JWT Bearer tokens, OAuth 2.0, roles and permissions, OWASP API Top 10.

Playwright API automation

APIRequestContext, CRUD tests, schema validation, auth fixtures, data-driven tests, framework design and CI/CD.

5 real projects

Portfolio-ready Playwright + TypeScript projects you can push to GitHub and discuss in interviews.

AI and interviews

Use AI to generate test cases and code faster, then prepare with hundreds of interview questions and a mock interview.

Practise on a Real API (No Sign-Up)

Most tutorials stop at theory. Here every lesson includes Send request boxes that call the SQA Tools practice API live. It has hardcoded users, products and orders, temporary objects you can create, update and delete, four authentication types, rate limits, delays and 141 ready-made test scenarios.

GEThttps://sqatools.in/wp-json/sqa-api/v1/users/1
curl -i \
  "https://sqatools.in/wp-json/sqa-api/v1/users/1"

Base URL: https://sqatools.in/wp-json/sqa-api/v1. Full endpoint list and scenarios on the API Testing Practice page.

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Your Learning Path

LevelModulesOutcome
Beginner1. Fundamentals · 2. HTTP essentialsUnderstand any API and read any request/response
Intermediate3. Authentication and security · 4. Manual testing (Postman, SoapUI)Test real APIs manually and design complete test cases
Advanced5. GraphQL, WebSocket, gRPC, contract, performance · 6. Playwright automationAutomate API suites in TypeScript and run them in CI
Job-ready7. Projects · 8. AI · 9. Interview preparationPortfolio, speed with AI, interview confidence

API Testing Course Syllabus

New lessons are published every week. Lessons marked “coming soon” are in progress.

Module 7: API Automation Projects

  1. Project 1: User Directory API Suite
  2. Project 2: CRUD and Optimistic Locking (coming soon)
  3. Project 3: Auth and RBAC Security Suite (coming soon)
  4. Project 4: Contract and Negative Testing (coming soon)
  5. Project 5: E-commerce API + UI with CI/CD (coming soon)

Module 8: AI for API Testing

  1. How to Use AI for API Testing (coming soon)
  2. AI Prompt Library for API Testers (coming soon)

Module 9: Interview Preparation

  1. API Testing Interview Questions (coming soon)
  2. REST API Interview Questions (coming soon)
  3. Postman Interview Questions (coming soon)
  4. SoapUI Interview Questions (coming soon)
  5. Playwright API Interview Questions (coming soon)
  6. Scenario-Based API Interview Questions (coming soon)
  7. API Testing Mock Interview (coming soon)
  8. API Testing Cheat Sheet (coming soon)
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The 5 Playwright + TypeScript Projects

  1. User Directory API Suite (beginner): pagination, filters, sorting, search and negative tests.
  2. CRUD and Optimistic Locking Framework (intermediate): full lifecycle, ETag, If-Match 412 and data expiry.
  3. Auth and RBAC Security Suite (intermediate): Basic, API key, JWT login, refresh, logout, tampered tokens and roles.
  4. Contract and Negative Testing Framework (advanced): JSON Schema contracts and data-driven boundary tests.
  5. E-commerce API + UI Hybrid with CI/CD (advanced): chained flows, UI cross-checks, Allure reports and GitHub Actions.

Who This Course Is For

  • Manual testers moving into API and automation testing.
  • Freshers and students preparing for QA and SDET interviews.
  • Automation engineers (Selenium, Cypress) adding API testing to their skills.
  • Developers who want to test their own APIs properly.

What You Need

  • A laptop with a modern browser. That’s enough for Modules 1 and 2.
  • Postman (free) and SoapUI open source for Module 4.
  • Node.js and VS Code for the Playwright modules. New to TypeScript? Start with the Playwright with TypeScript tutorial.
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API Testing Course FAQs

Is this API testing course free?

Yes. Every lesson, the practice API, the projects and the interview questions are free, with no sign-up.

Do I need coding knowledge to learn API testing?

No. Modules 1 to 5 cover manual API testing with tools like Postman and SoapUI and need no coding. Coding (TypeScript) is needed only for the automation modules and projects, and the course links to free TypeScript lessons.

Which tool is best for API testing?

Postman is the most popular for manual testing, SoapUI for SOAP services, and Playwright with TypeScript is an excellent choice for automation because it covers both UI and API testing in one framework.

How long does it take to learn API testing?

With one to two hours a day, most learners finish the fundamentals and manual testing in 3 to 4 weeks and become comfortable with API automation and the projects in another 4 to 6 weeks.

Is API testing a good career skill in 2026?

Yes. Modern applications are built from many services connected by APIs, so API testing appears in most QA, SDET and automation job descriptions, and it pairs well with AI-assisted testing skills.

Can I use the practice API for my own automation projects?

Yes. It’s built for practice: GET data is fixed, objects you create expire automatically, and it supports Basic, API key and JWT authentication. Please don’t send real personal data to it.

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