Lightweight service virtualization/ API simulation / API mocking tool for developers and testers

Over the wire test doubles

Eliminate API integration headaches with Specmatic's no-code AI-powered API development suite. Teams ship APIs 10x faster by transforming specifications into executable contracts instantly—no coding required, no integration surprises.

Camouflage is a backend mocking tool for HTTP, gRPC, Websockets and Thrift protocols, which helps you carry out your front end prototyping, unit testing, functional/performance testing in silos, in absence of one or more Microservices/APIs.

HTTP mock for Golang: record and replay HTTP/HTTPS interactions for offline testing

Java binding for Hoverfly

High-performance, multi-protocol mock server. HTTP, WebSocket, gRPC, MQTT, SSE, GraphQL, SOAP in one binary.

Service Virtualization Solution – a combined Service Stub and Transparent Proxy

🤖 AI-Mocks is a Kotlin-based toolkit for mocking and testing LLM APIs with real streaming and SSE support. Simulate OpenAI, Anthropic, Gemini, Ollama, and A2A services locally for reliable integration testing.

Stubbing tool for HTTP calls to allow more comprehensive + deterministic tests

A .Net Library for Hoverfly

A fluent Java API for virtualizing HTTP services. Service virtualization simplified. No endpoint configuration. Import/export of request-response pairs.

Bokor is a simple, Record and Playback Mock Server written in Node.js, utilized for Service Virtualization.

Service Virtualized HTTP - to help service test automation stay fast and consistent

⚡ Mokksy is a mock HTTP server for testing and simulating real-world API behavior, including streaming, SSE, delays, and failures. Built for Kotlin, Java, and modern distributed systems.

Stub and validate HTTP endpoints with ease.

Admin dashboard for Hoverfly

A mountebank client written in Go.

Servirtium Overview

Hoverfly integration for pytest