Top TESTING GitHub Repositories & Tools (2026)

syzkaller is an unsupervised coverage-guided kernel fuzzer

:mailbox: SMTP Server + Web Interface for viewing and testing emails during development.

Quick and Easy server testing/validation

MockServer is an HTTP(S) mock server and proxy for testing that lets you mock APIs, inspect and modify live traffic, and inject failures. It supports HTTP/1.1, HTTP/2, gRPC, WebSockets, TCP and more on a single port, with additional support for HTTP/3, message brokers, and AI/LLM APIs.

Full-stack testing PHP framework

A library to support tests with throwaway instances of Docker containers for all compatible .NET Standard versions.

An open-source, high-performance quantitative trading framework in C++/Python focused on strategy analysis and backtesting Trading model R&D · Ultra-fast engine · Efficient backtesting

Verify is a snapshot testing tool that simplifies the assertion of complex data models and documents.

Database Subsetting and Relational Data Browsing Tool.

Strategies for cleaning databases in Ruby. Can be used to ensure a clean state for testing.

Fluent testing assertions for Java and the JVM

Cucumber for golang

NUnit Framework

JavaScript API for Chrome and Firefox

Fast, multi-protocol credential brute-forcer. Parses Nmap, Nessus, and Nexpose output to automatically test default and custom credentials across 30+ protocols.

Additional Jest matchers 🃏💪

PHP Mutation Testing library

GO Feature Flag is a simple, complete and lightweight self-hosted cloud native feature flag solution 100% Open Source — built on OpenFeature 🎛️

The open source, cloud native tool for API Mocking and Testing. Microcks is a Cloud Native Computing Foundation incubating project 🚀

802.11 Attack Tool