Open-source alternatives to Httplab

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

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

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

Responses is a Python mocking library designed to intercept outgoing HTTP calls made with the Requests library to return predefined simulated responses. It functions as a request verification framework and a network simulation tool, allowing for the verification of application behavior against various API response patterns without making real network calls. The project distinguishes itself through a traffic recorder that captures real network interactions and saves them to files for deterministic replay. It further enables the simulation of complex network scenarios, including the triggering

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 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

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

Expose is a secure tunneling tool that creates public URLs for local development servers, making them accessible from the internet without complex network configuration. It forwards incoming HTTP requests and responses between a public relay server and a local machine, enabling external services to reach a development environment that would otherwise be isolated behind a firewall or VPN. The project distinguishes itself through a comprehensive set of webhook debugging and inspection capabilities. It captures all incoming webhook requests and displays them in a real-time dashboard or command-l

This project is a multi-protocol API simulation and mocking system designed to replace external dependencies during development and testing. It provides an API mocking server, a network traffic proxy, and specialized simulators for language model services and identity providers. The system distinguishes itself through deep AI simulation capabilities, including the emulation of language model providers and Model Context Protocol servers using JSON-RPC 2.0. It supports multi-turn conversational logic, state tracking for AI chat APIs, and the visualization of agent execution through call graphs

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

httpstat is a command-line utility for executing HTTP requests and analyzing network timing, response metadata, and connection performance. It serves as a diagnostic tool and debugger for inspecting HTTP headers and response bodies through a terminal interface. The tool focuses on performance analysis by measuring the latency of secure web requests, including the overhead of the TLS handshake and general connection timing. It provides color-coded output to visually separate request and response metadata for human analysis. The utility covers API integration testing and network troubleshootin

WebMock is a Ruby library for HTTP request stubbing, response simulation, and network interception. It serves as a test assertion framework for verifying outgoing HTTP traffic and a network interception layer that blocks external connections to prevent accidental requests during testing. The project provides capabilities for dynamic response generation and the sequencing of different return values for repeated requests to the same endpoint. It supports simulating network failures, such as timeouts or exceptions, and allows for response replays using raw HTTP data loaded from local files. The

ngxtop is a real-time web server dashboard and traffic analyzer that transforms raw Nginx access logs into immediate visual metrics. It functions as a live monitor for tracking request rates, response codes, and bandwidth usage by parsing server logs as they are written. The tool extracts performance data from combined, common, and JSON log structures. It uses these parsed logs to identify high-traffic endpoints and server error patterns for troubleshooting. The system processes log streams through a pipeline that includes schema-based extraction, record filtering via evaluatable expressions

htrace.sh is a command-line diagnostic suite designed for profiling web traffic, auditing security configurations, and analyzing network connectivity for remote endpoints. It functions as a shell-based orchestration tool that wraps standard system utilities to perform modular diagnostic tasks and infrastructure analysis. The tool distinguishes itself by providing a unified interface for both HTTP request debugging and automated security scanning. Users can customize request parameters, including headers, methods, and proxy settings, to simulate specific client behaviors. It further automates

Wuzz is an interactive command line HTTP client and request inspector designed for capturing, reviewing, and analyzing outgoing network calls and their payloads. It functions as a terminal-based tool for debugging API issues and testing web endpoints. The tool provides specialized filtering for response bodies, using regular expressions and format-specific query syntaxes tailored for JSON and HTML data. It allows for the persistence of captured requests and responses to disk to facilitate the reproduction of network issues and offline analysis. User settings and default request behaviors are

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

Karate is a Gherkin API testing framework and JVM test orchestrator designed for API validation, workflow automation, and browser automation. It provides a unified environment for executing scriptable logic on the Java Virtual Machine with thread-safe concurrent processing. The project includes a built-in HTTP mock server to simulate backend API behavior by delivering dynamic responses to intercepted requests. It also features a visual regression testing tool that detects interface changes by comparing screenshots against baseline images using pixel-matching analysis. The system supports API

Typhoeus is a Ruby wrapper for libcurl that functions as a session-based HTTP client. It provides an interface for making both synchronous and asynchronous network requests. The project acts as a parallel request manager, using a managed queue to execute multiple network requests concurrently. It further distinguishes itself as a mocking tool for stubbing requests with predefined responses and as a caching layer that stores responses to avoid redundant network calls. The library covers a broad range of capabilities including session cookie management, response body streaming for large files,

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

xh is a command-line HTTP client used for sending network requests, testing REST APIs, and debugging connections. It functions as a terminal-based tool for executing requests with custom headers and bodies, while providing built-in formatting for network responses. The project includes a generator that converts configured network requests into equivalent shell commands for use in a standard terminal. It also features a response formatter that applies syntax highlighting and custom formatting to response headers and bodies to improve readability. The tool covers a broad range of network capab

Chuck is an in-app network debugger and HTTP traffic logger for Android applications. It intercepts and records outgoing requests and incoming responses for OkHttp clients, providing an interface to monitor network activity and debug API interactions directly on a mobile device. The tool enables the inspection of network traffic through gzip decompression of compressed payloads and a search utility for filtering transactions by request paths or response codes. Captured interactions can be exported to external applications using the Android system share intent. The system manages data using l

VeryNginx is a Lua-based Nginx extension and programmable web application firewall. It provides a management control panel and a traffic monitoring dashboard to configure server settings and analyze request statistics without manual configuration file edits. The project implements a programmable security layer to filter malicious traffic and block common web attacks, such as SQL injection and directory traversal. It includes tools for bot traffic restriction through request rate limiting and browser identity verification. The system covers traffic management via URI routing and redirection,

Moya is a network abstraction layer for Swift that provides a structured framework for defining and executing REST API requests. It functions as a type-safe API client that decouples network endpoint definitions from the underlying implementation details to prevent configuration errors and URL typos. The project distinguishes itself by using protocol-based endpoint definitions and a provider-coordinated execution model. It includes a system for mapping network responses to strongly typed objects and features a dedicated tool for generating type-safe network interface files from external REST

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

Apihub is a deployable REST API mock server and public sandbox that provides a collection of functional endpoints for testing HTTP requests and building frontend portfolios. It serves as a pre-built backend infrastructure for simulating diverse services without requiring a custom backend. The project provides dedicated mock endpoints for various business domains, including ecommerce workflows, social networking features, realtime chat, and task management. It also includes specialized endpoints for verifying HTTP method behavior and header handling. The system implements a RESTful architectu