generate massive amounts of realistic fake data in Node.js and the browser

A toolkit with common assertions and mocks that plays nicely with the standard library

Most popular Mocking framework for unit tests written in Java

Mockery is a simple yet flexible PHP mock object framework for use in unit testing with PHPUnit, PHPSpec or any other testing framework. Its core goal is to offer a test double framework with a succinct API capable of clearly defining all possible object operations and interactions using a human readable Domain Specific Language (DSL).

Stub your network requests easily! Test your apps with fake network data and custom response time, response code and headers!

A tool for mocking HTTP services

PowerMock is a Java framework that allows you to unit test code normally regarded as untestable.

Seamless REST/GraphQL API mocking library for browser and Node.

Pester is the ubiquitous test and mock framework for PowerShell.

Axios adapter that allows to easily mock requests

A mock code autogenerator for Golang

HTTP client mocking tool for Python - inspired by Fakeweb for Ruby

Automatically mock your HTTP interactions to simplify and speed up testing

Development tool to mock API endpoints quickly and easily (docker image available)

Mock, Test & Track HTTP Requests and Response for Microservices

Lightweight service virtualization/API simulation tool for developers and testers

Over the wire test doubles

A friendly substitute for .NET mocking libraries.

Turn any OpenAPI2/3 and Postman Collection file into an API server with mocking, transformations and validations.

Boilerplate-free mocking framework for Swift!

Easy HTTP Networking in Swift a NSURLSession wrapper with image caching support

A minimal test double library for TDD with JavaScript

HTTP traffic mocking and testing made easy in Go ༼ʘ̚ل͜ʘ̚༽

The easy mocking library for .NET

Replace any .NET method (including static and non-virtual) with a delegate

Interface mocking tool for go generate

A lightweight library to simplify and generalize the process of writing unit tests for C applications.

Small library for mocking pymongo collection objects for testing purposes

Testing layer for Microsoft's HttpClient library. Create canned responses using a fluent API.

Javascript mocking library for WebSockets and Socket.IO