API Development & Testing

Python SDK, Proxy Server (AI Gateway) to call 100+ LLM APIs in OpenAI (or native) format, with cost tracking, guardrails, loadbalancing and logging. [Bedrock, Azure, OpenAI, VertexAI, Cohere, Anthropic, Sagemaker, HuggingFace, VLLM, NVIDIA NIM]

Fastest enterprise AI gateway (50x faster than LiteLLM) with adaptive load balancer, cluster mode, guardrails, 1000+ models support & <100 µs overhead at 5k RPS.

Free, open-source local AWS emulator.

Scalar is an open-source API platform:　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　🌐 Modern REST API Client　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　📖 Beautiful API References　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　✨ 1st-Class OpenAPI/Swagger Support

The Developer Platform for Modern APIs

A unified AI model hub for aggregation & distribution. It supports cross-converting various LLMs into OpenAI-compatible, Claude-compatible, or Gemini-compatible formats. A centralized gateway for personal and enterprise model management. 🍥

The open-source solution to building, maintaining, and collaborating on GraphQL Federation at Scale. The alternative to Apollo Studio and GraphOS.

The Cloud Native Application Proxy

The Cloud-Native API Gateway and AI Gateway

Open-source AWS emulator with a broad local cloud service surface.

The open-source, cross-platform API client for GraphQL, REST, WebSockets, SSE and gRPC. With Cloud, Local and Git storage.

Opensource IDE For Exploring and Testing API's (lightweight alternative to Postman/Insomnia)

⚡️ Open-source AI Gateway — Use any SDK to call 100+ LLMs. Built-in failover, load balancing, cost control & end-to-end tracing.

AI gateway, registry, and proxy for MCP, A2A, and REST/gRPC APIs.

Open-source API development suite for contract-first testing and specification-driven workflows.

Cloud-native gateway unifying multiple LLM providers.

Open-source platform for creating safe, isolated production sandboxes for API, integration, and E2E testing.

OpenAPI code generator for API clients, server stubs, and documentation.

🤖 AI Gateway | AI Native API Gateway

Envoy-based MCP gateway with auth and policy integration.

A lightweight AWS service emulator written in Go

Open source API gateway with native OpenAPI support.

REST API for any Postgres database

Test Automation Made Simple

Blazing fast, instant realtime GraphQL APIs on all your data with fine grained access control, also trigger webhooks on database events.

The open source, cloud native tool for API Mocking and Testing. Microcks is a Cloud Native Computing Foundation sandbox project 🚀

The Cloud-Native API Gateway and AI Gateway

Testcontainers for Go is a Go package that makes it simple to create and clean up container-based dependencies for automated integration/smoke tests. The clean, easy-to-use API enables developers to programmatically defi

🧙‍♀️ Move Fast and Break Nothing. End-to-end typesafe APIs made easy.

Tyk Open Source API Gateway written in Go, supporting REST, GraphQL, TCP and gRPC protocols

Gravitee.io - OpenSource API Management

KrakenD Community Edition: High-performance, stateless, declarative, API Gateway written in Go.

Open-source HTTP benchmarking platform for testing and proving API performance.

Hurl, run and test HTTP requests with plain text.

An interactive TLS-capable intercepting HTTP proxy for penetration testers and software developers.

Kubernetes-native API gateway for microservices built on Envoy Proxy.

Deterministic correctness testing for MCP servers.

Lightweight self-hostable API client with no cloud or telemetry.

API Dash is a beautiful AI-powered open-source cross-platform (Desktop & Mobile) API Client built using Flutter which can help you easily create & customize your HTTP & GraphQL API requests, visually inspect responses and generate API integration code. A lightweight alternative to postman/insomnia.

Open-source LLM API gateway with auth, multi-provider routing, and subscription-based access control.

High Performance GraphQL Runtime

Offline-first HTTP and socket API testing client for web and desktop.

PostgreSQL ➕ REST, low-code, simplify and accelerate development, ⚡ instant, realtime, high-performance on any Postgres application, existing or new

Open-Source API Development Ecosystem • https://hoppscotch.io • Offline, On-Prem & Cloud • Web, Desktop & CLI • Open-Source Alternative to Postman, Insomnia

A simple API client (postman like) in your terminal

Apache JMeter open-source load testing tool for analyzing and measuring the performance of a variety of services

🦍 The API and AI Gateway

Self-Hosted API Management for Builders

Open-source MCP gateway for enterprise AI.

Ultra performant API Gateway with middlewares. A project hosted at The Linux Foundation

Webhook gateway for sending, managing, and routing webhooks.

Cloud native, ultra-high performance AI&API gateway, LLM API management, distribution system, open platform, supporting all AI APIs.🦄云原生、超高性能 AI&API网关，LLM API 管理、分发系统、开放平台，支持所有AI API，不限于OpenAI、Azure、Anthropic Claude、Google Gemini、DeepSeek、字节豆包、ChatGLM、文心一言、讯飞星火、通义千问、360 智脑、腾讯混元等主流模型，统一 API 请求和返回，API申请与审批，调用统计、负载均衡、多模型灾备。一键部署，开箱即用。

Load balancer, API gateway, and reverse proxy with service discovery.

A Cloud Native traffic orchestration system

Free and open-source API Client & Interceptor.

API laboratory for designing and testing API workflows.

⚓️ Easily test HTTP webhooks with this handy tool that displays requests instantly.

API gateway for microservices.

Open-source, cloud-native, developer-centric API gateway.

AI-first IDE for QA and API testing.

NyaProxy acts like a smart, central manager for accessing various online services (APIs) – think AI tools (like OpenAI, Gemini, Anthropic), image generators, or almost any web service that uses access keys. It helps you use these services more reliably, efficiently, and securely.

The Grafbase GraphQL Federation Gateway

Webhook forwarding tunnel with CLI and dashboard.