API Testing Tools

Scalar

API Documentation

Scalar provides a modern toolkit for API documentation, request testing, and developer-facing API experiences built around OpenAPI.

Browserbase

AI Software Testing

Browserbase provides a reliable, managed browser infrastructure for AI agents, enabling web scraping, automated testing, and agent-based web interactions at scale.

StatusCake

Website Uptime Monitoring

StatusCake provides uptime monitoring, page speed testing, SSL monitoring, and hosted status pages for websites and APIs.

Kreya

API Testing Platforms

GUI client for gRPC, REST, and WebSocket APIs with scripting support and environment management.

Postman

API Testing Platforms

Postman is an API platform for designing, testing, documenting, and monitoring APIs with collaboration features for developer teams.

HTTP Toolkit

API Testing Platforms

Open source tool for debugging, testing, and building with HTTP and HTTPS traffic interception.

httpie

API Testing Platforms

Human-friendly command-line HTTP client for API testing providing intuitive syntax and JSON support.

Karate Labs

Test Automation Frameworks

Open source API testing framework combining test automation with API mocks and performance.

Pact

API Testing Platforms

Open source contract testing framework ensuring microservices communicate correctly by verifying API interactions between consumers and providers.

mitmproxy

Developer Tools

Open source interactive HTTPS proxy for intercepting, inspecting, modifying, and replaying web traffic for debugging.

Stubbornjava

Test Automation Frameworks

Lightweight framework for building mock HTTP servers in Java for integration testing of APIs.

Mockoon

API Testing Platforms

Desktop application for creating mock REST APIs with templating, response rules, and proxy mode for local development.

Hurl

API Testing Platforms

Command-line tool for running HTTP requests defined in plain text with assertions for testing APIs.

Mockbin

API Testing Platforms

Simple mock HTTP server by Kong for testing and debugging HTTP calls from your apps.

Playwright

API Testing Platforms

Playwright is an open-source end-to-end testing framework by Microsoft for testing web applications across Chromium, Firefox, and WebKit with a single API.

CircleCI

Code Security Scanning

CircleCI is a continuous integration and delivery platform that automates build, test, and deployment pipelines. It supports cloud and self-hosted environments with powerful parallelism and...

Hoppscotch

Product Ops Platforms

Hoppscotch is an open-source API development platform providing a fast, lightweight alternative to Postman for testing REST, GraphQL, WebSocket, and MQTT APIs.

Microcks

API Testing Platforms

Open source Kubernetes-native tool for mocking and testing APIs and microservices from OpenAPI and AsyncAPI specs.

Mailjet

Subscription Management

Mailjet by Sinch is an email delivery and marketing platform with collaborative editing, API sending, and real-time analytics for teams.

Apifox

API Design Tools

Chinese-founded API design, debugging, and testing platform used globally.

Checkly

AI Software Testing

Checkly is a monitoring-as-code platform for API monitoring and end-to-end testing that integrates with CI/CD pipelines to detect issues before they affect users.

REST-assured

A/B Testing

Java library for testing and validating REST services with a domain-specific language for writing readable API tests.

MSW

API Testing Tools

API mocking library for JavaScript that intercepts network requests using Service Workers for browser and Node.js testing.

Bruno

API Testing Platforms

Open source API client that stores collections directly in your filesystem using a plain text markup language.

Charles Proxy

API Testing Tools

HTTP proxy and monitor tool enabling developers to view HTTP and SSL traffic between their machine and the internet.

Hoverfly

A/B Testing

Lightweight API simulation tool for creating HTTP service virtualizations to enable fast parallel development and testing.

Swagger

API Testing Platforms

Swagger by SmartBear provides API design, documentation, testing, and governance tools built around the OpenAPI specification standard for API-first development.

Beeceptor

API Testing Platforms

Mock HTTP server and request inspector providing instant endpoints for testing and prototyping APIs.

Artillery

A/B Testing

Modern load testing and smoke testing tool for APIs and web apps with a focus on developer experience and CI/CD integration.

Mailgun

Email Deliverability Tools

Mailgun by Sinch is a transactional email API service for developers, providing email sending, receiving, validation, and deliverability optimization.

SoapUI

API Testing Platforms

Open source API testing tool by SmartBear supporting REST, SOAP, and GraphQL with assertion-based validation.

Loadster

API Testing Platforms

Distributed load testing for websites and APIs.

WireMock

API Testing Tools

Flexible API mocking tool for testing microservices and APIs by simulating HTTP-based APIs for reliable integration testing.

Fiddler

Developer Tools

Web debugging proxy from Progress logging HTTP/HTTPS traffic for debugging web application issues and testing APIs.

Checkmarx

Supply Chain Planning

Checkmarx provides a comprehensive application security platform including software composition analysis, SAST, DAST, and API security for enterprise DevSecOps programs.

Wiretap

API Testing Tools

Open-source OpenAPI-aware HTTP proxy for validating API requests and responses against schemas in real time.

Thunder Client

API Testing Platforms

Lightweight REST API client extension for VS Code with collections, environments, and Git-friendly storage.

httpbin

API Testing Platforms

HTTP Request & Response Service written in Python for testing HTTP clients and APIs.

Sinch Email Mailosaur

Email Deliverability Tools

Email and SMS testing for developers.

Dredd

API Documentation

Language-agnostic HTTP API testing tool that validates API documentation against its backend implementation.

Workbench

Developer Tools

Web-based Salesforce administration tool for developers.

Prismic

Headless CMS

Prismic is a headless page builder and CMS that enables marketers to build pages independently while developers maintain code quality.

Cobalt

AI Software Testing

Cobalt provides Pentest as a Service combining a vetted community of pentesters with a SaaS platform for on-demand security testing.

Keploy

Test Automation Frameworks

Open-source testing toolkit auto-generating test cases from API traffic for fast regression testing.

Nected

Workflow Automation

Nected is a low-code decision intelligence platform that unifies rule engines and workflow automation for backend process management and experimentation.

PostHog

API Testing Tools

PostHog is an open-source, all-in-one product analytics platform offering event analytics, session replay, feature flags, A/B testing, and a customer data platform with transparent usage-bas...

OneSignal

API Testing Tools

OneSignal is a customer messaging platform specializing in push notifications, email, SMS, and in-app messaging, serving over a million developers and businesses with a generous free tier.