Top 21 API Automation Testing Tools

You could be spending months developing your app’s UI and making it interactive and appealing for your customers. But what if it throws a fit the moment they try to search for a product or make a payment?

APIs act as a bridge between your app and backend systems to fulfil customer requests. If you leave any core functionality untested, your API might crash or expose your app to serious security risks.

So, how do you ensure your APIs are robust and work as expected even under high traffic? By automating API testing. In this blog, we will discuss all the top API testing tools, their features, benefits, and challenges in detail. 

What is an API?

Application Programming Interface (API) is a mechanism that allows two software components to interact with each other and transfer data using a set of rules and protocols. It allows developers to integrate data and services from other applications, rather than building them from scratch. 

What are API Automation Testing Tools?

API testing is a type of software testing that evaluates the quality of APIs to ensure they meet functionality, performance, and security standards. In recent years, there has been an expansion in interest in API/Web services testing. 

Having the right tools and solutions for API automation tests and an efficient strategy is becoming increasingly important; API testing is critical for a successful CI/DevOps practice.

Benefits of API Automation Tools

1. Faster release cycles

API automation testing tools focus on the app’s core functionality at the API layer which allows you to execute tests even before the UI is developed. You can detect bugs and issues within APIs early in the development cycle, before your app reaches the customers. Plus, faster testing cycles let you release feature updates frequently to improve customer experience.

2. Optimized test coverage

API automation testing tools drill down to the layers beneath the app’s interface to check if the databases are communicating with each other correctly. This ensures all integration points are checked at once leading to better test coverage and ultimately improving software quality. 

3. Reduced maintenance efforts

API automation tests are more stable than GUIs and resistant to frequent UI changes. The API tests remain reliable as the UI evolves and ensure critical business logic functions as intended without getting affected by visual or layout adjustments.

4. Language agnostic

Most API automation testing tools communicate using standard data formats and protocols like JSON and XML. This means you can work in any language you are comfortable with, whether it’s JavaScript, Ruby, Python, or PHP, and integrate with frameworks without language barriers.

5. Improved security

API automation tools identify vulnerabilities like mishandled data, poorly secured authentication, and gaps in access control. It ensures your app can handle real-world threats by focusing on encryption and permissions. 

21 API Automation Testing Tools 

1. TestGrid

TestGrid is an AI-powered end-to-end testing platform designed for both web and mobile applications. It provides secure and scalable infrastructure to run tests on real devices and browsers through on-premise setups or cloud services, making it adaptable for teams of any size.

By supporting API, UI, server, and database testing, TestGrid helps ensure comprehensive quality validation while fitting seamlessly into modern CI/CD pipelines.

Features

• Perform visual testing to detect even minor UI deviations in your app
• Use the record-and-play button to record actions, create test scripts, and automate tests
• Test your app’s code-level functionality before executing UI tests to identify subtle flaws that might become significant issues during GUI testing
• Test your APIs without writing a single line of code manually or rerunning any test case
• Use its unique Screen Broadcasting Turbo Mode makes remote access to iOS devices smooth and responsive—even in low-bandwidth environments

Pros	Cons
Supports multiple languages, including Python, JavaScript, PHP, Ruby, and Java Offers API automation for SOAP and REST calls Delivers detailed analytics and real-time monitoring to quickly surface issues and improve agility	While TestGrid supports codeless automation, its breadth of features can feel overwhelming for smaller teams

Pricing

• Freemium: $0 per month (200 minutes per 2 minute session)
• Manual Testing: $25 per month (5 users, 1 parallel test)
• End-to-End Automation: $99 per month (5 users, 1 parallel test)
• Private Dedicated: Starts from $30 per month (5 users, 1 dedicated device)
• Enterprise (On-premise/Hosted): Custom pricing

2. Postman

Postman is an API automation testing tool that lets you design, build, test, and collaborate on APIs. It maintains a directory of over 100,000 public APIs and supports specifications, including GraphQL, OpenAPI, and RAML. 

Features

• Test your API’s performance, behavior, and reliability using a JavaScript-based library of code snippets
• Use the Collection Runner to chain all API requests together, run them in specific sequences, and log results
• Store values in variables within dedicated testing environments, and use them in any request’s headers, body, or URL

Pros	Cons
Integrates with various third-party monitoring tools like New Relic, Datadog, and Opsgenie Lets you run collections and tests within your CI/CD pipeline using Newman or Postman CLI	Might get slow when working with very large collections or responses Higher memory usage compared to native applications

Pricing

• Free: $0
• Basic: $14 per user per month
• Professional: $29 per user per month
• Enterprise: $49 per user per month

3. SoapUI

SoapUI is an API automation tool for testing and debugging SOAP and REST APIs that operate within a client/server infrastructure. It lets you perform functional testing, regression testing, interoperability testing, and performance testing. You can even record the tests and use them later. 

Features

• Use DataSource TestStep to read and loop test data from external files, including XML, Excel, JDBC, and files
• Use Test Debugging to improve your test quality and follow test flows, properties, variables, and context
• Examine if your API is vulnerable to stack overflows using the XML Bomb Scan

Pros	Cons
Offers a user-friendly graphical interface to make test creation, management, and execution easier without extensive coding knowledge Lets you mock services to simulate API behavior when actual services are in development	Running tests on large scale projects with huge datasets might lead to performance issues Advanced features are only available in commercial versions

Pricing

• Open-source

4. REST assured

Rest Assured is a Java library that allows you to test and validate REST APIs. It offers a DSL which makes it easier for you to create readable and maintainable test cases, and supports HTTP requests like POST, GET, PUT, DELETE, PATCH, and HEAD.

Features

• Test response status code, body, message, and headers using the Rest Assured library
• Write readable test cases in the DSL and send HTTP requests, and verify HTTP responses
• Test API authentication using methods like Basic, Digest, Form, and OAuth

Pros	Cons
Supports JSON and XML request/response payloads Integrates with Java testing frameworks like TestNG and JUnit	Limited performance and GUI testing Isn’t suitable for teams working with languages other than Java

Pricing

• Open-source 

5. Karate

Karate is an API automation testing tool that lets you write tests without extensive coding knowledge. It supports data-driven testing, authentication handling, and multipart file upload testing. Also, it integrates with Selenium for browser-based testing.

Features

• Write HTTP requests and assertions in language-neutral Gherkin DSL
• Run multi-threaded parallel tests for integration and end-to-end testing to dramatically cut down on execution time
• Use the Karate-Gatling plugin to convert .feature files into Gatling simulations to enable performance testing without duplicating scripts

Pros	Cons
Integrates with CI and project build tools like Maven, Gradle, Jenkins, and JUnit5 Supports tables, examples, dynamic payloads, and CSV-driven test cases natively	Verbose DSL for complex flows that involve conditional logic or dynamic payloads Lacks advanced debuggers or step-through features

Pricing

• Open-source

6. Apigee

Apigee is one of the automation tools for API testing by Google that allows you to design, secure, deploy, monitor, and scale your API tests. It helps you automate tedious tasks like API documentation and SDK creation so you can focus on core business logic.

Features

• Generate OpenAPI specifications in natural language in Cloud Code and Gemini chat using the @mention functionality
• Orchestrate and manage traffic for complex apps in any style, including REST, SOAP, gRPC, and GraphQL to ensure control and reliability
• Configure Apigee hybrid to deploy your APIs in your own data center or public cloud

Pros	Cons
Offers monetization support  for your API products Includes built-in dashboards to investigate spikes in traffic and identify areas for performance improvement	Supports only Google Cloud solution Limits proxies to 60 per environment, which leads to hardware costs and scaling issues

Pricing

• Custom pricing available

7. Tavern

Tavern is a pytest based API testing framework that offers a simple, concise, and flexible YAML syntax to help you write and customize complex tests. You can integrate Tavern into your own test framework or use the command-line tool tavern-ci.

Features

• Use the Pytest-Allure integration to generate test reports with the test stages that were run, the responses, any fixtures used, and errors
• Mark tests as expected to fail temporarily, so that they can be fixed later, or skip certain tests using the ‘mark’ function
• Reuse parts of the code to see if they return the same or  a different response using the ‘Anchors’ feature

Pros	Cons
Supports both MQTT and REST protocols to test IoT or message-driven systems Offers powerful assertion capabilities for API validation	Doesn’t offer performance or security testing Primarily focuses on integration testing, hence not suitable for unit testing APIs

Pricing

• Open-source

8. HTTPie

HTTPie is a command-line HTTP client that lets you test, debug, and interact with HTTP APIs and servers. It has built-in JSON support and is compatible with Linux, macOS, and Windows. You can integrate HTTPie right into your CI/CD workflows and automate HTTP requests.

Features

• Create requests in natural language by typing your prompt directly on HTTPie’s URL field, or in the AI dialogue box
• Modify any placeholders or errors in the request directly from the dialogue box before saving it
• Generate an HTTP request by describing components like URLs, headers, and body by asking the AI

Pros	Cons
Offers an easy and clean command-line interface Include extensive documentation with clear guides to help you get started quickly1	Requires Python installation which adds an extra step in setup Navigating intricate requests like authentication might be complex

Pricing

• Open-source 

9. ReadyAPI

ReadyAPI is an API automation tool that lets you create, manage, and execute security, functional, and performance tests. You can build complex tests using data-driven loops and simulate massive loads on your web servers to check how it functions under stress.

Features

• Run large regression and lightweight tests in parallel at scale and catch issues early without slowing development
• Use TestEngine to automatically stage and schedule tests based on availability 
• Access test execution results when needed with persistent result tracking 

Pros	Cons
Integrates smoothly with CI/CD tools like Jira Offers scripting and connectivity to external data sources like Excel and PDF files	Relatively pricey subscription plans Might lead to performance and memory issues when dealing with large and complex apps

Pricing

• API Test Module: $1085 per license
• API Performance Module: $8209 per license
• API Virtualization Module: $1575 per license

10. Hoppscotch

Hoppscotch is one of the best automation tools for api testing for web apps that’s lighweight. It’s compatible with all platforms, including Windows, Mac, and Linux. You can even host Hoppscotch on your own server and use it with your team.

Features

• Save, organize, and share your API requests with collections by accessing them from the side panel
• Organize your requests, collections, and environments into different workspaces and invite your team to collaborate 
• Keep a track of your previous requests and responses by accessing the ‘history’ icon from the side panel

Pros	Cons
Offers unlimited workspaces, collaborators, and collections Lets you self-host your instance of the application	Doesn’t simulate real-world usage and load testing APIs Smaller community and less extensive documentation

Pricing

• Free: $0
• Organization: $6 per user per month
• Enterprise: $190 per user per month

11. RapidAPI

RapidAPI is an API hub where you can find, test, and connect with thousands of APIs with just one API key. You can keep your APIs private or share them with the public and monetize them.

Features

• Use the drag and drop feature editor to set up different tests for your APIs
• Write test scripts right inside the RapidAPI testing platform to validate API headers and prevent API injections
• Run tests on different data centers globally to check performance of your API based on geographical locations

Pros	Cons
Track API usage using real-time analytics and dashboards Supports REST APIs, SOAP APIs, GraphQL, and Kafka	Offers a large marketplace which might be difficult to adopt for beginners Monetization payouts might be subject to significant commissions

Pricing

• Basic: $0 per month
• Pro: $9.99 per month
• Ultra: $99 per month
• Mega: $999 per month

12. Insomnia

Insomnia is an API client that allows you to configure and create query parameters for dynamic and complex requests. It offers built-in support for authentication methods like OAuth, API keys, and JWT tokens.

Features

• Use Insomnia CLI to automate execution of your API tests using your existing Git workflows
• Run unlimited tests in parallel and instantly detect errors or breaking changes
• Create comprehensive API tests for every collection with pre-response and pre-request scripting

Pros	Cons
Offers a clean and intuitive interface that’s easy to navigate for beginners Includes advanced features like environment variables, code generation, and GraphQL support	Lacks extensive documentation and resources Limited support for SOAP APIs

Pricing

• Hobby: $0
• Pro: $12 per user per month
• Enterprise: $45 per user per month

13. Assertible

Assertible is an API automation tool for testing and monitoring. It allows you to define test cases using a simple interface and supports HTTP methods like GET, POST, PUT, and DELETE. It integrates with tools like Slack and Zapier.

Features

• Use deployments API to test your web app after every deployment to uncover errors quickly
• Encode your business logic into assertions and monitor the uptime and availability of all your critical APIs
• Automatically sync your API tests with latest changes by updating responses, parameters, and headers

Pros	Cons
Offers real-time monitoring of API tests with alerts Lets you collaborate with your team to test business logic and communicate failures	Only supports automated API testing Free users can only add two APIs to their account

Pricing

• Personal: $0
• Standard: $25 per month
• Startup: $50 per month
• Business: $100 per month

14. Mockoon

Mockoon is an automation tool for mocking REST APIs. You can create mock servers locally without writing code and integrate them into your existing workflows by using a CLI, Docker image, and several libraries.

Features

• Deploy your mock APIs online with Mockoon Cloud, sync them across all devices, and share them with your team
• Use text editor to modify body content in multiple languages, including JSON and HTML
• Create unlimited mock APIs on unlimited number of routes and run them in parallel

Pros	Cons
Provides customization options to create mock APIs that mimic the behavior of real APIs Offers straightforward setup process, ensuring less time is spent on configuration	Lacks advanced features like sophisticated data validation for complex authentication methods Limited documentation and resources, which make adopting advanced features challenging

Pricing

• Solo Plan: $15 per month
• Team Plan: $29 per user per month
• Enterprise Plan: custom pricing

15. Swagger

Swagger is an automation tool that allows you to describe the structure of your APIs and automatically build interactive API documentation. It does this by asking your API to return a JSON or YAML that includes a detailed description of your API.

Features

• Use Swagger Editor to create your APIs directly in your browser with syntax auto-completion and real-time feedback
• Enforce design standards by using reusable templates and style validators
• Use built-in mocking, linting, and validation tools to automate quality checks in every step of API lifecycle

Pros	Cons
Lets you generate code for client SDKs and server stubs Offers version control and collaboration with teams	Doesn’t support load testing or security testing natively Limited support for SOAP APIs

Pricing

• Individual: $22.80 per user per month
• Team: $34.44 per user per month
• Enterprise: $58.80 per user per month
• Enterprise Plus: custom pricing

16. Runscope

Runscope is an API automation testing tool that allows you to monitor, test, and debug web-services APIs. You can run tests on cloud-based, on-prem, and hybrid environments and integrate with communication platforms like Slack and Flowdock.

Features

• Use notification tools like PagerDuty, HipChat, and webhooks to monitor API performance and get alerts about downtime and breakages
• Connect with third-party analytics solutions like Datadog, Splunk, and New Relic Insights to catch and debug API problems 
• Build chained requests with simple template syntax and insert dynamic data into requests like timestamps and IDs

Pros	Cons
Integrates with CI/CD tools like Jenkins, CircleCI, and AWS CodePipeline Centralizes all API validations into one accessible platform	Steeper learning curve for complex tests like chained API calls and OAuth authentication Doesn’t offer an open-source version

Pricing

• Small: $79 per month
• Medium: $199 per month
• Large: $599 per month
• Premier: custom pricing

17. Apiary

Apiary is an API automation testing tool that lets you design, document, and test APIs. It offers you a user-friendly interface to create interactive documentation, test endpoints, and create API blueprints.

Features

• Define APIs, outline endpoints, methods, and query parameters using a simple and readable API Blueprint
• Simulate API interactions to create mock API servers from API Blueprint definitions
• Use the version control features to track changes to the API specification and manage different versions

Pros	Cons
Offers a collaborative design environment where developers, designers, and stakeholders can contribute Includes a comprehensive and interactive API documentation	Lacks features like automated integration testing, security testing, or load testing Isn’t compatible with protocols like WebSockets or gRPC

Pricing

• Custom pricing is available

18. Hypertest

Hypertest is a no-code automation tool that autogenerates integration tests from network traffic. It lets you test code and service dependencies by automatically generating and updating mocks, making it one of the best API automation testing tools.

Features

• Use the record mode to monitor all requests hitting a service, including all interactions between components (inputs, responses, and outgoing calls)
• Switch to test mode to execute all the requests captured during the record phase to generate actual response of the service
• Run tests as automated checks pre-commit or with a pull request to release new changes bug-free

Pros	Cons
Integrates with CI/CD tools, including Jenkins, GitLab, Travis CI, and CircleCI Supports gRPC, REST, and GraphQL services	Difficult configuration for inter-service mocking Supports only Java and Node.js

Pricing

• Starter: Free trial
• Enterprise: Custom pricing

19. RestSharp

RestSharp is an API automation testing tool to make synchronous and asynchronous calls to remote resources over HTTP. It supports C# library and OAuth1, OAuth2, and JWT for authentication.

Features

• Make calls using XML or JSON body, and RestSharp takes care of serializing requests and deserializing responses
• Add a query, URL, or URL-encoded form parameters with just one line of code
• Configure content headers, including disposition and type of content, and handle responses coming from remote endpoints

Pros	Cons
Easy to configure with .NET application Allows customization for every parameter of the HTTP call	Supports only .NET compatible languages Doesn’t have built-in GUIs, mocks, or test orchestration

Pricing

• Open-source

20. JMeter

JMeter is among the best API automation testing tools specifically designed for load testing and performance measurement on APIs. It’s based on Java and can extract data from HTML, JSON, XML, or any text format.

Features

• Simulate heavy loads on servers, group of servers, or network to measure the performance of APIs
• Include assertions for every HTTP request to test the functional behavior of the APIs
• Track performance metrics, such as error rates, response times, and throughput rates to spot bottlenecks and optimize performance

Pros	Cons
Supports multiple protocols including HTTP, HTTPS, SOAP, REST, and FTP Provides real-time reports on latency and resource usage	Doesn’t support Ajax, JavaScript, and Flash Steep learning curve to use advanced features

Pricing

• Open-source

21. WireMock

WireMock is an API automation tool for mock testing that helps you create stable test and deployment environments. You can simulate various HTTP interactions and test how your app responds to latency, errors, and status code.

Features

• Create mock APIs in code, as JSON files, via REST APIs, and by recording HTTP traffic proxied to another location
• Mock HTTP requests and responses with record and play, dynamic stubbing, and proxying
• Perform fault injection testing to assess error-handling logic

Pros	Cons
Offers both synchronous and asynchronous API behaviors Supports XML, JSON, and SOAP APIs	Focus on API mocking rather than functional testing Doesn’t have native support for non-HTTP protocols

Pricing

• Open-source

Challenges in API Testing

1. Handling complex API architectures

As apps become more sophisticated to offer flexibility and improved performance to the customers, intricate API architectures, such as microservices and hybrid models increase complexity in testing.

Microservices, for example, operate independently, which requires testing individual services’ functionality. This multi-layered testing structure demands a meticulous testing approach.

2. Security and authentication

Some common security threats in APIs include cross-site scripting (XSS), unauthorized data access, and SQL injection attacks. APIs are a prime target for attackers because they access sensitive customer data. Even a small loophole in the testing process can lead to disastrous data breaches.

3. Improper documentation

A common issue developers face during API testing is dealing with outdated, sparse, or even missing documentation. Without a comprehensive understanding of all the features of an automation tool, there’s a risk of errors and inefficiencies while performing testing. 

Ensure Reliable Releases with Consistent API Testing

With growing customer demands and tighter release cycles, continuous API testing with every code change is critical. Even a small loophole can lead to degraded customer experience, potential security threats, and increased costs.

Therefore, it’s essential to incorporate automated API testing into your workflows right from the development phase to ensure your APIs get validated with every commit. 

Start a free trial with TestGrid today, and integrate API testing into DevSecOps pipelines.