Open-source alternatives to Webmock

OHHTTPStubs is an HTTP network mocking library and request interceptor used to simulate server responses for testing application behavior without a live backend. It functions as a network request stubbing tool that captures outgoing network calls and replaces them with predefined mock data, custom status codes, and headers. The library distinguishes itself through its ability to simulate a wide range of network conditions, including artificial latency and connection failures. It supports dynamic response sequencing, allowing the tool to return a series of different responses for the same requ

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

MPX is a cross-platform framework designed to build applications for multiple mini-program ecosystems and the web from a single codebase. It utilizes a static transpilation pipeline to transform source code into platform-specific bundles, employing a single-file component system that encapsulates templates, logic, and styles. The framework provides a reactive state management system that automatically synchronizes application data with the user interface through computed properties and watchers. The project distinguishes itself through a robust build-time toolchain that supports sub-package p

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 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

OkHttp is an HTTP client for the JVM and Android that enables network communication via synchronous and asynchronous requests. It provides a core identity as a comprehensive networking toolkit featuring a WebSocket client for bidirectional data synchronization, a TLS security toolkit for encrypted communication, and a programmable HTTP mock server for simulating backend responses. The project distinguishes itself through a specialized security and performance architecture. It implements mutual TLS, certificate pinning, and DNS over HTTPS to secure data in transit, while utilizing connection p

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

This project is a comprehensive guide and collection of best practices for testing Node.js backend applications. It provides a curated set of patterns and reference examples for writing reliable unit, integration, and component tests. The project distinguishes itself through specific strategies for backend integration, including detailed methods for API contract testing against OpenAPI specifications and shared schemas. It offers specialized guidance on managing message queue testing, focusing on idempotency, resilience, and asynchronous event synchronization. The guide covers a broad range

Jest is a JavaScript testing framework designed for writing and running automated test suites to verify the correctness of JavaScript and TypeScript code. It functions as a comprehensive toolset that integrates a test runner, a mocking and spying library, a snapshot testing tool, and a code coverage tool. The framework distinguishes itself through snapshot testing, which records the serialized state of data structures to detect regressions in future executions. It also includes a mocking and spying library for simulating external dependencies and tracking function calls to isolate code during

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

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

WireMock is a suite of tools for service virtualization, providing mock servers for HTTP APIs and WebSocket communication. It serves as an HTTP API mock server and request verifier, allowing for the simulation of responses and the interception of network requests to test client applications without a live backend. The project differentiates itself through a service virtualization model that records real network traffic and replays it as stubs to mimic external service behavior. It includes a network fault injector to simulate response delays and connectivity issues, and a stateful scenario ma

Interactsh is an out-of-band security testing framework and interaction server designed to detect vulnerabilities such as server side request forgery and blind injections. It functions as a multi-protocol interaction collector that captures DNS, HTTP, and SMTP requests to verify outbound communication from remote applications. The project provides a self-hosted interaction gateway for managing unique payloads and gathering network interactions across multiple domains. It distinguishes itself through the ability to simulate various network protocols and response behaviors, including the routin

Axios is a promise-based HTTP client used to make asynchronous network requests in both browser and Node.js environments. It functions as a multi-environment network adapter that abstracts the transport layer to ensure consistent behavior across different runtimes. The project distinguishes itself through a request lifecycle management system that allows for the cancellation of active requests, the setting of timeouts, and the monitoring of upload and download transfer progress. It includes a mechanism for intercepting network traffic, enabling the transformation of outgoing requests and inco

Millennium is a modding framework for the Steam desktop application designed to inject custom code, scripts, and styles into the client's Chromium rendering engine. It functions as a system for applying custom themes, loading dynamic plugins, and intercepting network requests. The project provides a dynamic plugin loader to extend application functionality without requiring a restart and a telemetry blocker to intercept outgoing network requests for analytics and crash reporting. It includes a tool for modifying the visual appearance of the application via a live editor that supports real-tim

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

This project is a request testing service and diagnostic utility designed to help developers inspect HTTP interactions and verify client-side network logic. It functions as a stateless server that echoes request metadata, including headers, parameters, and body content, back to the calling client to ensure data is transmitted as intended. The service distinguishes itself by providing a platform for mocking REST API endpoints and simulating various server behaviors. Developers can use these endpoints to trigger specific HTTP status codes, test content negotiation, validate form data encoding,

go-sqlmock is a Go library that simulates SQL driver behavior for unit testing by intercepting database calls through the standard database/sql/driver interface, eliminating the need for a real database connection. It provides a comprehensive mocking framework that allows developers to define expectations for SQL operations, including queries, executions, prepared statements, and transaction lifecycles, with precise control over the results and errors returned. The library distinguishes itself through its flexible matching and verification capabilities. It supports regex-based or exact SQL

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

MSW is a JavaScript API mocking library and integration testing tool designed to intercept network requests at the network level. It allows for the definition of mock data and status codes using routing syntax to simulate server responses without requiring changes to the application source code. The project utilizes a service worker to proxy API calls in the browser, providing a mechanism for isolated frontend development and testing. It employs platform-specific network adapters to maintain a consistent mocking interface across both browser and Node.js environments. The library covers a ran

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

Adblock4limbo is a collection of JavaScript-based scripts and tools designed for web content filtering and advertisement blocking. It functions as a content filter and user script suite that removes pop-ups, banners, and trackers from websites. The project includes a bilingual web translator for side-by-side content translation, an M3U8 video link extractor for retrieving direct stream URLs, and a web content filter specifically designed to remove sponsored links and content farm entries from search engine results. Its capabilities extend to network traffic management, including request filt

Mailpit is an SMTP mail testing server and web-based email inbox designed to intercept and store outgoing emails for development and integration testing without delivering them to real recipients. It functions as an SMTP mocking tool and relay gateway, allowing users to capture mail traffic and view it through a browser interface. The project distinguishes itself by providing tools for SMTP server simulation, including the ability to inject failure codes to test application resilience. It also includes an email compatibility analyzer that validates HTML rendering, checks link integrity, and s

req is a chainable HTTP client library for Go designed to simplify request configuration and automatic response decoding into structures. It provides a fluent-interface request builder that allows developers to incrementally define request properties and encapsulate HTTP logic into reusable API SDKs. The project distinguishes itself with a TLS fingerprint emulator that mimics browser network signatures to bypass bot detection and crawler filters. It also includes a concurrent file downloader that increases transfer speeds by fetching large remote files in parallel segments. The library cover

ngxluawaf is an OpenResty web application firewall that uses Lua to filter malicious HTTP requests and block web attacks. It operates as a programmable request filter and IP access controller for Nginx, providing a security layer to identify and block unauthorized scanners, fuzzing attempts, and abnormal network requests. The project includes capabilities for HTTP layer 7 DDoS mitigation by restricting request frequency per IP address. It further secures the environment by restricting access to sensitive archives and blocking script execution in upload directories to prevent data leakage.