API testing is crucial for building reliable applications, but why pay when you can use powerful free tools?
Whether you're a developer, tester, or DevOps engineer, these free API testing tools will streamline your workflow and boost productivity.
✅ 1. Postman (Free Plan)
📌 Website: https://www.postman.com/
🔹 A user-friendly API platform that supports REST, SOAP, and GraphQL.
🔹 Free tier includes API testing, automation, and monitoring.
🔹 New in 2025: AI-powered test generation for faster scripting.
✅ 2. Hoppscotch
📌 Website: https://hoppscotch.io/
🔹 A lightweight, web-based alternative to Postman.
🔹 Supports REST, GraphQL, and WebSockets.
🔹 Open-source and completely free.
✅ 3. Insomnia (Community Edition)
📌 Website: https://insomnia.rest/
🔹 A clean, minimal API testing tool with great UI.
🔹 Supports REST, GraphQL, and gRPC.
🔹 Free version includes environment variables and automated requests.
✅ 4. Karate DSL
📌 GitHub Repo: https://github.com/karatelabs/karate
🔹 Open-source API testing framework with built-in performance testing.
🔹 Supports REST, SOAP, and GraphQL.
🔹 Ideal for automation & CI/CD integration.
🔹 Example Test Case in Karate:
Feature: Test API with Karate
Scenario: Verify GET request
Given url 'https://jsonplaceholder.typicode.com/posts/1'
When method GET
Then status 200
And match response.id == 1✅ 5. REST Assured (Java-based)
📌 Website: https://rest-assured.io/
🔹 Java library for testing REST APIs.
🔹 Works well with JUnit, TestNG, and Spring Boot.
🔹 Ideal for backend developers.
🔹 Example API Test with REST Assured:
import static io.restassured.RestAssured.*;
import static org.hamcrest.Matchers.*;
public class APITest {
public static void main(String[] args) {
given()
.when().get("https://jsonplaceholder.typicode.com/posts/1")
.then().statusCode(200)
.body("id", equalTo(1));
}
}✅ 6. Tavern (For Python Testers)
📌 Website: https://taverntesting.github.io/
🔹 API testing tool for Python developers.
🔹 Integrates with Pytest for powerful automation.
🔹 Supports REST and MQTT.
✅ 7. Swagger Inspector
📌 Website: https://swagger.io/tools/swagger-inspector/
🔹 Free online API testing tool from Swagger.
🔹 Helps generate OpenAPI documentation.
🔹 No installation required – works directly in the browser.
✅ 8. Katalon Studio (Free API Testing)
📌 Website: https://www.katalon.com/api-testing/
🔹 GUI-based API testing tool with built-in automation.
🔹 Free for individuals and small teams.
🔹 Supports REST, SOAP, and GraphQL.
✅ 9. PyRestTest
📌 GitHub Repo: https://github.com/svanoort/pyresttest
🔹 A lightweight, command-line API testing tool for Python.
🔹 Ideal for performance testing.
🔹 Supports JSON validation and automation.
✅ 10. SoapUI (Free Version)
📌 Website: https://www.soapui.org/
🔹 Open-source tool for SOAP and REST API testing.
🔹 Supports functional, security, and performance testing.
🔹 Free version includes most features except API mocking & advanced reporting.
💡 Which One Should You Use?
🔹 Postman & Hoppscotch – Best for everyday API testing.
_ 🔹 Karate & REST Assured_ – Great for automated & performance testing.
_ 🔹 Insomnia & Swagger Inspector_ – Lightweight and easy-to-use tools.
🔹 Tavern & PyRestTest – Perfect for Python-based API testing.
💬 Which free API testing tool do you use?
Drop your recommendations in the comments!
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