Open-source alternatives to Wiremock

Mockserver is a multi-protocol mock server and API verification proxy used to simulate HTTP, gRPC, and WebSocket endpoints. It functions as a tool for testing client applications without relying on live backend services, providing a system to simulate chat completions and streaming responses for large language model integrations. The project automates behavior by generating request expectations and response behaviors from OpenAPI and Swagger specification files. It differentiates itself through a network traffic simulator that introduces latency, dropped connections, and failures to verify ho

Mockoon is an HTTP API simulation platform and design tool used to create fake API endpoints that simulate server responses without a backend. It functions as an OpenAPI mock server tool and a JSON API mocking utility, allowing for the rapid iteration of API contracts and the generation of response templates. The project distinguishes itself through a combination of stateful mocking, using a local JSON database to simulate CRUD operations, and the ability to run as a headless API mock server via a command line interface. It supports real-time collaborative editing and AI-assisted prototyping

httplab is an HTTP mock server and interactive API simulator used to analyze incoming request payloads and simulate custom HTTP responses for application testing. It functions as a request inspector that captures and displays real-time details of HTTP headers and bodies sent by clients. The project includes a response management system that imports and stores predefined HTTP response templates using JSON files. This allows for the persistence of request and response configurations to local files for use in reusable testing scenarios. The tool provides capabilities for generating custom HTTP

moco is a multi-protocol mock server and programmable API stub used to simulate HTTP, REST, WebSocket, and Server-Sent Events endpoints. It enables the creation of fake backend services to facilitate development and integration testing without requiring a live server. The project distinguishes itself through its ability to act as a network traffic replay tool, capturing real request-response pairs via a proxy and playing them back locally. It also supports bidirectional communication simulations, including WebSocket server simulation and SSE stream simulation with configurable delivery delays

nock is a Node.js HTTP mocking library and request interceptor. It captures outgoing network traffic to specific hosts and paths, returning predefined responses to decouple applications from external servers during automated testing. The project functions as an API expectation framework to verify that specific calls were made with correct parameters. It includes a traffic recorder that captures real network interactions as fixtures for playback and a network simulation tool to introduce artificial latency or trigger network errors. Its capabilities cover request matching via hostnames, paths

Linkerd is a Kubernetes service mesh that manages network traffic between microservices. It functions as a transparent networking proxy, layer 7 traffic manager, and mutual TLS security layer, providing observability and reliability for service-to-service communication without requiring changes to application code. The project distinguishes itself through a sidecar-proxy architecture that intercepts TCP and application-level traffic to provide automatic mutual TLS encryption and identity verification. It enables cross-cluster service networking to link multiple clusters and implements cloud-n

Mirage JS is a browser-based mock server and client-side API simulator designed for JavaScript application development. It functions as a mocking tool that intercepts network requests to simulate backend API behavior, allowing developers to build and test frontend interfaces without requiring live backend infrastructure. The tool provides a simulation layer that mimics REST endpoints to facilitate rapid prototyping of user flows and application logic. It enables the creation of fake server responses directly within the web browser to verify how an application handles various data scenarios an

Moto is a cloud service mockery framework and API mock server that simulates AWS infrastructure locally. It allows developers to test cloud-dependent code and verify infrastructure-as-code templates without deploying real resources or incurring costs. The project functions as an SDK interceptor that can patch existing service clients to redirect requests to a local mock environment. It can also be run as a standalone HTTP server, enabling any programming language to interact with the simulated endpoints. The framework covers a vast array of simulated capabilities, including data storage, com

Nock is a Node.js HTTP mocking library used to intercept outgoing network requests and return predefined responses. It functions as a network request interceptor and HTTP mock server, allowing developers to simulate external API behavior for automated testing without making live network calls. The project includes an API fixture recorder to capture real network interactions and save them as reusable data files for playback. It also features a network latency simulator that introduces artificial delays to outgoing HTTP responses to verify timeout handling and race conditions. The library prov

httplab is an interactive HTTP mock server, request inspection tool, and response simulator. It functions as a web server designed to capture and analyze incoming HTTP requests and headers in real time for debugging purposes. The tool enables the construction and delivery of custom HTTP responses to simulate various server behaviors. Users can forge specific headers and bodies to test how client applications handle different status codes and payloads, with the ability to save these configurations as response templates for consistent reuse across sessions. The project covers a broad surface o

Clumsy is a Windows network fault injection tool that intercepts system-wide network traffic at the kernel level using the WinDivert driver, without requiring proxy configuration or application code changes. It captures and manipulates packets for all running applications, including localhost connections, enabling controlled testing of application behavior under degraded network conditions. The tool provides comprehensive network impairment capabilities including latency simulation, bandwidth throttling, packet loss, corruption, duplication, and reordering. Users can apply these impairments s

VCR is a Ruby library that records and replays HTTP interactions during test runs, storing them in serialized cassette files. It captures real HTTP requests and responses, then serves those recorded responses instead of making actual network calls, enabling fast and deterministic test suites that work offline. The library provides configurable request matching, allowing comparisons based on method, URI, host, path, body, or headers to find the correct recorded response. It supports scheduled cassette re-recording to automatically refresh stored interactions at a configurable interval, keeping

Fetch-mock is a testing utility designed to isolate application code from external network dependencies by intercepting and overriding outgoing traffic. It functions as a network request interceptor that captures calls made via the Fetch API, allowing developers to simulate server responses and verify application behavior without requiring a live backend infrastructure. The library distinguishes itself through a unified interface that provides consistent network interception logic across diverse runtime environments, including browsers, service workers, and server-side platforms. By replacing

Pollyjs is an HTTP mocking and recording library designed to capture and replay network interactions to create deterministic tests. It functions as a request interceptor and stubbing framework that records real API responses into files, ensuring consistent test results across different environments without relying on live network servers. The tool utilizes pluggable network adapters to support various environments and employs a state-based mode switching system to toggle between recording, replaying, and stubbing behaviors. It uses pattern-based request matching and persistent interaction sto

TUnit is a comprehensive C# testing framework, mocking library, and fluent assertion tool. It utilizes source generation for test discovery and mock creation, ensuring compatibility with Native AOT and IL trimming by eliminating the need for runtime reflection and proxies. The framework provides specialized capabilities for integration testing, including the management of distributed application lifecycles, isolated database schemas, and the correlation of telemetry and logs across process boundaries via OTLP. It also includes an HTTP testing utility to intercept network exchanges and mock AP

Prism is a set of tools for generating mock servers and validation proxies based on OpenAPI specifications or Postman collection files. It serves as an API contract testing tool to verify that API implementations adhere to formal contracts. The project provides an OpenAPI mock server that simulates API responses and a validation proxy that checks live HTTP traffic against an OpenAPI specification to identify implementation discrepancies. It also includes a mock server capable of mimicking API behavior based on exported Postman Collection files. The tool covers API behavior simulation and tra

This library provides a utility for intercepting and simulating HTTP requests within the Axios ecosystem. It functions as an HTTP request interceptor that allows developers to define mock responses for outgoing network traffic, enabling frontend integration testing and development without requiring live backend infrastructure. The tool distinguishes itself by offering granular control over the request lifecycle, including the ability to match specific request patterns and forward unmatched traffic to actual destinations. It supports the simulation of unstable network environments by injecting

Goravel is a full-featured development scaffold and framework for building web applications, REST APIs, and gRPC services using the Go programming language. It implements a model-view-controller architecture and provides a comprehensive toolkit for high-performance remote procedure call servers and clients. The framework is distinguished by its extensive integrated ecosystem, which includes a fluent object-relational mapper for database management and a dedicated command-line interface toolkit for administrative automation and project scaffolding. It features a driver-based service abstractio

pydoll is a Chrome DevTools Protocol automation library and headless browser controller used for web data extraction and parallel browser automation. It controls Chromium-based browsers via direct WebSocket connections, allowing it to manage isolated browser contexts and tabs while bypassing the overhead and detection associated with WebDriver. The project features an anti-bot evasion framework that mimics natural human behavior, including mouse movements generated via Bezier curves and variable typing patterns. It provides specialized stealth capabilities to bypass behavioral analysis and au

Taiko is a browser automation framework and web end-to-end testing library used to perform programmatic user actions and verify application behavior. It functions as a headless browser testing tool capable of simulating real interactions and asserting page states in Chromium and Firefox. The project includes a browser interaction recorder that captures live actions and exports them as executable JavaScript automation scripts. It also serves as a web accessibility auditor, analyzing pages to detect accessibility violations and ensure compliance with inclusive design standards. The framework c

Postcat is an integrated platform for API design and documentation, serving as a REST API client and a mock server. It provides a workspace to define technical requirements and data schemas, allowing development teams to align on interface behavior. The platform features a plugin architecture that enables the integration of third-party tools and custom capabilities. It decouples frontend and backend development cycles by generating simulated server responses based on predefined data structures. The toolset includes an environment management system for switching between development, staging,

Dva-boot-admin is a single-page application framework designed for building administrative dashboards using React, Redux-based state management, and component libraries. It provides a modular frontend architecture combining declarative routing, state management wrappers, and pre-built dashboard layouts with navigation shells and data tables. The framework organizes application features around isolated functional domains, encapsulating views, state models, and data services within dedicated folders. It features config-driven generation capabilities that automatically render complete data table

Mock is a JavaScript API mocking tool and network request interceptor designed to decouple front-end development from back-end progress. It functions as an API simulation tool and mock data generator, allowing developers to build user interfaces and high-fidelity prototypes by mimicking the request and response cycle without a live server. The system provides a mechanism for intercepting outgoing HTTP calls and returning simulated data. It enables front-end prototyping by generating synthetic datasets to validate application behavior during automated testing cycles and development. Capabilit

Proxyman is a cross-platform HTTP debugging proxy that captures, inspects, and modifies HTTP, HTTPS, and WebSocket traffic. It functions as a man-in-the-middle proxy, decrypting SSL/TLS traffic to allow real-time inspection and modification of encrypted requests and responses. The tool is designed for debugging web and mobile applications, with capabilities for API mocking and simulation, scriptable traffic modification, and team collaboration on network logs. What distinguishes Proxyman is its deep integration with mobile and cross-platform development workflows. It provides automated certif

swagger-node is a toolkit for OpenAPI API development that ensures a project's implementation matches its documented design. It enables the generation of functional API servers and interactive documentation directly from YAML specification files. The project features a system for mapping API endpoints to specific controller functions and a mock mode that simulates API responses from the specification. This allows for API prototyping and frontend development before backend business logic is implemented. The platform provides a command-line interface for project bootstrapping, server managemen

Vue-typescript-admin-template is a TypeScript-based admin panel starter built with Vue CLI 3, providing a complete foundation for building enterprise back-office interfaces. It enforces type safety across Vue components using TypeScript, reducing runtime errors and improving code maintainability, while offering a dynamic route permission system that controls sidebar navigation and page access by mapping user roles to route permissions at runtime. The template includes a mock API service layer that simulates backend responses for frontend development without a live server, along with internati