Open-source alternatives to Mockserver Monorepo

Atmosphere is a Java-based framework for building and coordinating AI agents. It provides a real-time transport layer for streaming data via WebSockets, SSE, gRPC, and WebTransport, alongside a multi-agent orchestration framework for managing agent fleets through sequential, parallel, and graph-based execution workflows. The project features a durable workflow engine that persists agent state as snapshots, allowing long-running tasks to survive system restarts and incorporate human-in-the-loop approvals. It also implements Model Context Protocol servers to expose tools, resources, and prompt

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

PraisonAI is an autonomous AI agent platform that coordinates multiple LLM-powered agents for research, planning, and execution of complex workflows. It functions as a multi-agent orchestration framework, a workflow builder, and a Model Context Protocol server, while also providing retrieval-augmented generation through vector knowledge bases. Agents can interact via CLI, web, or standardized protocols with sandboxed code execution. The platform distinguishes itself with a rich set of agent communication protocols, including A2A, REST, WebSocket, voice and telephony integration, and MCP, allo

Connexion is a spec-first Python web framework designed to derive server behavior and validation logic directly from a predefined API contract. It enables the development of web services by using an OpenAPI specification to automatically handle routing, request validation, and response serialization. The framework distinguishes itself by acting as an OpenAPI request validator and mock server. It can simulate API behavior by serving example responses based on specification schemas, allowing for frontend development and prototyping before a backend implementation is completed. Additionally, it

This platform serves as a centralized web interface for managing, executing, and reporting on automated API test suites and manual endpoint validation tasks. It provides a comprehensive environment for RESTful service testing, allowing users to organize projects, track team access, and maintain a clear history of execution results to monitor system stability. The platform distinguishes itself by integrating a mock server that generates synthetic responses for API endpoints, enabling client-side development and testing before backend services are fully implemented. It supports complex testing

This project provides a web-based integrated development environment for defining, documenting, and simulating software interface specifications. It serves as a browser-based modeling tool that enables teams to create structured API contracts using the RAML modeling language. The environment distinguishes itself through its modular design, which allows the modeling interface to be embedded directly into existing web applications and developer portals. It supports a plugin architecture that enables the integration of custom persistence layers and metadata handlers, allowing teams to attach pro

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,

mcp-use is a development framework designed for building, deploying, and managing servers, clients, and autonomous agents using the Model Context Protocol. It provides a comprehensive toolkit for creating servers that expose custom tools, data resources, and prompts to compatible AI agents. The project distinguishes itself by offering a complete lifecycle for protocol-based applications, including a dedicated hosting platform for production servers and a compliance validator to ensure servers meet marketplace publishing requirements. It also features an observability suite for tracing protoco

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

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

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

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

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

This project is a terminal-based log analyzer and real-time traffic monitoring system designed for web server environments. It processes raw server access logs to generate structured statistical insights, providing visibility into visitor behavior, bandwidth usage, and request latency. The tool functions as a high-performance utility capable of handling large-scale datasets through multi-threaded parsing and memory-efficient data structures. The software distinguishes itself by offering both an interactive terminal interface and a web-based dashboard that updates in real-time via WebSocket st

This project is a web-based management interface designed for the administration, monitoring, and configuration of Nginx server instances. It functions as a centralized platform for managing reverse proxy settings, traffic routing, and server lifecycles, providing a visual dashboard to replace manual configuration file editing. The platform distinguishes itself through integrated infrastructure automation and observability tools. It supports distributed environments by synchronizing configuration states across multiple nodes and containerized services, while offering artificial intelligence a

mcp-go is a Go implementation of the Model Context Protocol (MCP) providing an SDK and framework for building servers that connect large language model applications to external tools and data sources. It serves as a developer kit for implementing bidirectional communication and structured data exchange between AI clients and servers. The framework enables the creation of executable tools with structured output schemas, reusable prompt templates, and data resource exposure via URI templates. It supports multiple transport layers, including stdio, HTTP, and Server-Sent Events, using a transport

This project is an Android RPA framework designed for automating user interfaces and system tasks on rooted Android devices using Python and ADB. It provides a suite of tools for rooted device management, allowing for programmatic control of system settings, application lifecycles, and shell command execution via a remote API. The framework distinguishes itself through a combination of dynamic instrumentation and AI integration. It can inject scripts into running processes to hook Java interfaces and modifies application behavior in real time. Additionally, it supports large language model in

The Model Context Protocol C# SDK is a library for building clients and servers that implement the Model Context Protocol to integrate AI tools and resources. It provides an AI tool integration framework and a multi-modal content handler to exchange text, images, and binary resources between AI models and external context providers. The SDK utilizes a JSON-RPC communication library to manage bidirectional data exchange. It features a transport-agnostic communication layer that supports standard input and output, HTTP, and in-memory pipes, with specific integration for ASP.NET Core hosting. T

mcp-agent is a framework for building AI agents that integrate with Model Context Protocol servers to execute tools and access data. It functions as a multi-agent orchestrator and protocol-compliant server, enabling the creation of agents that can discover and invoke tools from connected external servers. The project distinguishes itself through a durable workflow engine that supports long-running tasks capable of pausing, resuming, and surviving restarts. It implements complex orchestration patterns, including iterative evaluator-optimizer loops, hierarchical workflow nesting, and specialist

This project provides a translation layer and set of adapters designed to bridge AI agents with the Model Context Protocol. It functions as an integration layer that allows agents to operate as protocol-compliant servers and enables the conversion of protocol-based tools into formats compatible with agent frameworks and logic graphs. The adapters facilitate tool interoperability by wrapping external protocol tools for use within agent workflows and exposing internal agent capabilities to any client implementing the Model Context Protocol. This creates a communication bridge that supports inte

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

TablePro is a cross-platform database management client designed for browsing, querying, and administering both SQL and NoSQL databases. It functions as a unified workspace that integrates a code-centric SQL editor with schema visualization tools, allowing developers to manage complex data models and execute queries across diverse database engines. The application distinguishes itself through an agentic AI integration layer that connects language models directly to database tools, enabling automated query generation, optimization, and error fixing with configurable approval gates. It features

Kreuzberg is a document extraction engine that converts PDFs, Office files, images, and over 90 other formats into clean, structured text and metadata. It is built around a compiled Rust core that can be used as a native library, a command-line tool, a REST API server, or a WebAssembly module for browser-based processing. The system is designed to run entirely on self-hosted infrastructure, with no data leaving the user's environment. What distinguishes Kreuzberg is its breadth of integration surfaces and its pipeline architecture. It exposes extraction capabilities through native bindings fo

The Google Workspace CLI is a command-line interface and Google API client designed to automate tasks across Google Workspace services. It functions as a cloud productivity automator that uses the Google Discovery Service to dynamically generate command structures and parameter requirements at runtime. The project distinguishes itself by providing a specialized AI agent toolset, exposing a server over standard input and output to provide structured tool definitions and skills for AI clients. It includes security layers for AI content sanitization to protect against prompt injection and utiliz

This project is a Model Context Protocol server that enables Large Language Models to control Playwright browsers for web automation, scraping, and end-to-end testing. It functions as a programmable interface for executing JavaScript, capturing screenshots, and interacting with web elements across multiple browser engines. The server exposes browser automation capabilities as a set of standardized tools that models can discover and invoke. It supports session-based browser isolation to ensure unique contexts for each client connection and provides a transport layer using either standard input

Plow is a suite of utilities used for generating HTTP load, measuring network performance, and visualizing live metrics. It functions as both an HTTP load generator and a benchmarking tool that measures latency and throughput by sending concurrent requests at configurable rates. The project includes a Socks5 and HTTP proxy client, allowing benchmark traffic to be routed through proxies to test services located behind network gateways. It also provides a real-time performance dashboard via web and terminal interfaces to visualize live metrics and latency histograms during active sessions. The

Yakit is a comprehensive cybersecurity all-in-one platform designed for security assessments. It integrates a suite of core tools including an HTTP interception proxy for real-time traffic modification, an out-of-band interaction detector for verifying remote command execution via TCP, DNSLog, and ICMP, and a reverse shell manager for controlling remote server connections. The platform is distinguished by its dedicated security scripting environment, which allows for the development and execution of custom logic and plugins using a specialized high-performance language. It further extends fun