# rest-api

Wafer-scale inference at thousands of tokens per second

Cerebras Inference serves open-weight LLMs like Llama, Qwen, and GPT-OSS on wafer-scale CS-3 chips through an OpenAI-compatible API, benchmarking between 1,800 and 2,600 output tokens per second on Llama 3.1 8B and several hundred on 70B models. A free tier offers one million tokens per day with no credit card, while paid pay-per-token pricing starts at $0.04 per million tokens for the smaller Llama models.

Customer engagement infrastructure for developers

Knock is flexible notification and customer engagement infrastructure built for developers and AI agents. Send messages across email, SMS, push, chat, and in-app channels from a single API. Features AI-native journey building with single-prompt workflows, advanced segmentation with dynamic attributes, in-app messaging with custom components, data unification across warehouse and CDP, and version control with rollbacks. Delivers hundreds of millions of messages monthly with 99.99% uptime.

Open-source multi-protocol API client

Firecamp is an open-source API DevTool supporting REST, GraphQL, WebSocket, and Socket.IO protocols as a lightweight alternative to Postman. It provides IntelliSense, team collaboration with shared workspaces, and seamless import from OpenAPI, Insomnia, AsyncAPI, and HAR formats. Each protocol gets a dedicated testing playground with response metrics including time, size, and status codes.

Versatile microservice framework for any protocol

Armeria is an open-source microservice framework from the creator of Netty at LINE Corporation that supports gRPC, Thrift, REST, and GraphQL on a single server and port. It provides built-in decorators for metrics, distributed tracing, load balancing, authentication, rate limiting, circuit breakers, and automatic retries. The framework integrates seamlessly with Spring Boot, Dropwizard, and Reactive Streams while serving automated API documentation with interactive request testing.

Email API service that gives AI agents their own inboxes and identities

AgentMail is a YC S25 startup that provides email infrastructure specifically designed for AI agents. It gives each agent its own email address and inbox, enabling agents to send, receive, and manage email conversations independently. With $6 million in seed funding from General Catalyst and Paul Graham, and over 500 B2B customers, AgentMail solves the identity and communication gap that arises when organizations deploy autonomous agents that need to interact via email.

Batteries-included full-stack framework for React, Node.js, and Prisma

Wasp is an open-source full-stack web framework that brings the Rails-like batteries-included experience to the JavaScript ecosystem. It uses a declarative configuration file to define auth, database models, server operations, and routing, then compiles to a standard React and Node.js application with Prisma for data access. With 18,000+ GitHub stars and YC backing, Wasp eliminates boilerplate while giving AI coding agents clear structure and guardrails.

AI-native API gateway by Alibaba with MCP server hosting and LLM routing

Higress is an open-source AI-native API gateway developed by Alibaba that combines traditional API management with LLM-specific capabilities like token-based rate limiting, model routing, prompt caching, and MCP server hosting. Built on Envoy and Istio, it provides enterprise-grade traffic management while natively understanding AI workload patterns including streaming responses, long-lived connections, and multi-model fallback chains.

Open-source financial data platform for quants, analysts, and AI agents

OpenBB is an open-source financial data platform that normalizes data from 100+ providers into a unified Python SDK, REST API, and Excel Add-in. It serves as the open-source alternative to Bloomberg Terminal for developers building fintech applications, quantitative research pipelines, and AI-powered financial analysis tools. With over 65,000 GitHub stars and SOC 2 Type II certification, it is one of the most popular open-source developer tools for financial data.

Multi-model database for the AI era — document, graph, vector, and relational in one

SurrealDB is a multi-model database that natively combines document, graph, relational, key-value, and vector storage in a single engine. It eliminates the need for separate databases by handling structured queries, graph traversals, full-text search, and vector similarity in one SQL-like query language called SurrealQL. Built in Rust for performance and safety, it supports real-time subscriptions, row-level permissions, and embedded or distributed deployment modes.

Cost-effective AI inference platform with 86+ models from $0.02/M tokens

DeepInfra is an AI inference platform offering 86+ LLM models with pricing starting at $0.02 per million tokens. Backed by $20.6M in funding including an $18M Series A from Felicis Ventures, it provides OpenAI-compatible endpoints for models including DeepSeek, Llama, and Mistral with pay-as-you-go pricing.

Zero-config conversion of FastAPI endpoints into MCP tools

FastAPI-MCP automatically converts existing FastAPI endpoints into Model Context Protocol tools with zero configuration. With 11,700+ GitHub stars, it is the most popular MCP integration layer, enabling thousands of FastAPI developers to make their APIs accessible to AI agents like Cursor and Claude through the MCP standard.

World's largest API hub and marketplace

RapidAPI is the world's largest API hub and marketplace connecting developers to thousands of public and private APIs through a single platform. Provides a unified interface for discovering, testing, and managing API connections with standardized authentication, billing, and monitoring. Features an API testing playground, code snippets in multiple languages, team workspaces, and analytics dashboards. Used by millions of developers to integrate third-party services with a single API key.

Thread-based AI assistant API with tools and file support

OpenAI's platform API for building stateful AI assistants. Manages conversation threads, supports function calling, code interpreter, and file search (RAG) out of the box. Usage-based pricing makes it accessible for startups and enterprises alike, with built-in memory and tool orchestration for production-grade conversational applications.

Open-source API client

Hoppscotch is a free, open-source API development ecosystem for building, testing, documenting, and collaborating on APIs through a lightweight, fast web-based interface. It supports REST, GraphQL, WebSocket, MQTT, SSE, and Socket.IO protocols. With over 2.5 million users and 5 million+ monthly API requests, Hoppscotch has become a leading open-source alternative to Postman for developers who prioritize speed, simplicity, and self-hostable workflows.

Human-friendly HTTP client

User-friendly CLI HTTP client for testing and debugging APIs with intuitive syntax, colorized output, and JSON highlighting. Simpler than curl with sensible defaults — auto JSON formatting, persistent sessions, and auth helpers. Also available as HTTPie Desktop (GUI) and HTTPie for Web (browser-based). Supports HTTPS, proxies, file uploads, and plugins. 34K+ GitHub stars. The developer-friendly curl alternative for API work.

Git-friendly offline API client

Open-source API client for testing REST, GraphQL, and gRPC APIs as a lightweight, privacy-focused alternative to Postman. Stores API collections as plain files in your Git repository for easy version control and team collaboration. Features environment variables, scripting, collection runner, and a declarative syntax called Bru. Offline-first with no cloud account required. Available on macOS, Windows, and Linux. 29K+ GitHub stars and growing rapidly among developers leaving Postman.

Open-source API client

Open-source API client by Kong for designing, debugging, and testing REST, GraphQL, gRPC, and WebSocket APIs. Features a clean interface with environment variables, authentication helpers, code generation, cookie management, and response timeline. Supports OpenAPI and Swagger specs for design-first workflows. Git Sync for version-controlled API collections. Available on macOS, Windows, and Linux. A popular alternative to Postman with stronger focus on privacy and local-first usage.

API development and testing platform

The most popular API platform used by 30M+ developers worldwide. Build, test, and document APIs with collections, environments, automated testing, and team collaboration. Features mock servers, monitoring, API design tools, and a vast public API network. The industry standard for API development workflows from prototyping through production testing and documentation.

OpenAPI-powered developer portals

OpenAPI documentation renderer with a clean three-panel layout that generates beautiful, responsive API reference pages from your OpenAPI spec. Available as open-source React component or CLI-generated static site. Supports code samples in multiple languages, search, and deep linking, making it the go-to choice for teams who want polished API docs without custom development.

API for GPT-4, o1, DALL-E, Whisper, and embeddings

Official API platform for GPT-4o, o1/o3 reasoning models, DALL-E image generation, Whisper speech-to-text, and text embeddings. Features Assistants API, function calling, JSON mode, fine-tuning, and batch processing. The most widely used AI API in the industry, powering millions of applications from chatbots to complex multi-step agent systems across every sector.

Direct API access to Claude models with tool use

Official API for Claude models including Opus, Sonnet, and Haiku. Supports tool use, computer use, extended thinking, and batch processing. Features prompt caching, streaming, and Messages API with vision capabilities. Known for strong performance on complex reasoning tasks, nuanced instruction following, and safety-conscious design that makes it trusted for enterprise and production applications.

Google Cloud ML platform with Gemini and custom models

Google Cloud's end-to-end ML platform with Gemini models, Model Garden featuring 150+ models, AutoML, and custom training pipelines. Features Vertex AI Search, Conversation, and Agent Builder for enterprise AI applications. The comprehensive platform for organizations building production AI systems at scale within the Google Cloud ecosystem, with enterprise governance and compliance built in.

OpenAI models with Azure enterprise security

Microsoft's enterprise gateway to OpenAI models — GPT-5, o3, GPT-realtime, GPT-audio — with Azure security, compliance, and global infrastructure. Azure OpenAI keeps data within the customer's tenant (no OpenAI training), offers zero-trust architecture, private endpoints, dedicated capacity, Microsoft Agent Framework integration, and Azure AI Studio for orchestration. 80,000+ enterprise customers.

Managed foundation models on AWS

Fully managed AWS service providing enterprise access to 100+ foundation models from Anthropic, Meta, Mistral, Cohere, and Amazon's Nova family through a single API. Bedrock includes AgentCore for agent runtime, Knowledge Bases for RAG, Guardrails blocking 88% of harmful content, plus Model Distillation, Prompt Caching, and Intelligent Prompt Routing for cost optimization.