# REST API

Ultra-fast LPU inference for open-weight models

Groq is an AI inference provider built around custom Language Processing Unit (LPU) hardware for low-latency open-weight model serving. GroqCloud exposes an OpenAI-compatible API for Llama, GPT-OSS, Qwen, Kimi, DeepSeek, Gemma, Whisper, and related models, with high token-throughput positioning, model-specific rate limits, and usage-based pricing.

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.

Low-cost reasoning and coding models with V4 API options

Chinese AI research lab developing low-cost reasoning and coding models with a fast-moving hosted API surface. Current API docs foreground DeepSeek V4 Flash and V4 Pro with thinking/non-thinking modes, OpenAI- and Anthropic-compatible endpoints, 1M context, JSON output, tool calls, and chat-prefix/FIM options. Free chat assistant and API access are available, while open-weight/self-hosting claims should be checked against current model repositories.

The GitHub of ML — model hub, datasets, and inference

Open-source platform for building, sharing, and deploying machine learning models and datasets. Hosts 500k+ models, 100k+ datasets, and Spaces for interactive demos. The central hub of the open-source AI ecosystem, providing model discovery, inference APIs, and collaborative tools that make it the GitHub of machine learning for researchers and developers worldwide.

Open-weight inference, fine-tuning, and GPU-cloud platform

Together AI is a cloud platform for running, fine-tuning, batching, and training open-weight AI models. It supports serverless inference, dedicated endpoints, LoRA and full fine-tuning, GPU clusters, code-execution sandboxes, and async batch jobs up to 30B tokens per model. Current docs list fast-moving families such as Qwen, Kimi, GLM, GPT-OSS, DeepSeek, Llama, MiniMax, and Mistral.

Open-weight frontier lab with Vibe, Studio, and a European AI cloud

Mistral AI is the French frontier-AI lab behind open-weight and commercial models, Mistral Vibe (formerly Le Chat), Studio, agentic coding, and the European-hosted Mistral Compute cloud. It gives developers an EU-centered alternative across API, assistant, agent-platform, and sovereign-infrastructure workflows, with model-specific licensing and pricing that should be checked per workload.

API for GPT-5 family models, multimodal generation, embeddings, and agents

Official API platform for the GPT-5 family, reasoning/thinking variants, multimodal generation, speech, embeddings, and agent workflows. Features the Responses API, tool calling, structured outputs, batch processing, fine-tuning, and SDK support. It remains one of the most widely integrated AI APIs in the developer ecosystem, but model choice, retention settings, rate limits, and pricing tiers require active governance in production.

Run and deploy ML models via API with simple pricing

Cloud platform that lets developers run thousands of open-source and proprietary public ML models through a simple API without managing GPUs or infrastructure. Replicate hosts models for image, text, audio, and video, supports Cog-based custom deployments and private models, and now operates as a distinct Cloudflare brand with pay-by-time or input/output pricing depending on the model.

Unified API gateway for 200+ AI models

Unified API gateway providing access to 500+ AI models from leading providers through a single OpenAI-compatible interface. OpenRouter eliminates the need to manage separate keys, billing, and integrations across providers like OpenAI, Anthropic, Google, and Meta, with built-in plugins for web search, PDF processing, automatic fallback routing, and per-model cost tracking.

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.

xAI conversational AI with real-time X/Twitter data

Conversational AI by xAI with real-time access to X (Twitter) data and web search. Excels at current events, humor, and unfiltered responses. SuperGrok plan includes advanced reasoning, image generation, and DeepSearch capabilities. Positioned as the AI assistant most connected to real-time social discourse, with unique strength in analyzing trending topics and public sentiment from the X platform.

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. 44K+ GitHub stars and growing rapidly among developers leaving Postman.

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 across web, desktop, and CLI clients. With 79K+ GitHub stars, 2.5M+ users, and 5M+ monthly API requests, Hoppscotch has become a leading open-source alternative to Postman for developers who prioritize speed, simplicity, and self-hostable workflows.

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.

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.

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.

OpenAI models with Azure enterprise security

Microsoft's enterprise gateway to OpenAI models — GPT-5-family models, reasoning variants, real-time/audio options, and Azure-hosted governance — with Azure security, compliance, and global infrastructure. Azure OpenAI is designed for teams that need OpenAI capability inside existing Microsoft cloud controls.

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.

Enterprise AI for text generation, search, and RAG

Enterprise-focused AI platform from former Google Brain researchers offering Command (chat), Embed (semantic search), and Rerank (result ordering) model families. Cohere Embed v4 supports 100+ languages with multimodal text/image inputs, North agent workspace processes documents and spreadsheets, and Model Vault enables secure VPC or on-premises deployment for regulated enterprises.

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.

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.

Production-grade inference with serverless and on-demand GPUs

High-performance inference platform serving open-source and custom AI models at global scale, processing 13+ trillion tokens daily at ~180K requests per second. Fireworks AI delivers 1,000+ tokens per second on large models through quantization-aware tuning and adaptive speculation, with serverless, fine-tuning, and dedicated GPU options across text, image, and audio modalities.

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.

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.

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 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.

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.

IBM-backed ContextForge gateway for federating MCP, A2A, REST, and gRPC APIs

MCP Context Forge is IBM’s Apache-2.0 ContextForge project for operating a gateway, registry, and proxy across MCP servers, A2A agents, REST APIs, and gRPC services. It centralizes discovery, authentication, policy controls, federation, and observability, with deployment paths through PyPI, Docker, and Kubernetes.

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.

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.

Beautiful, personalized API docs

Developer hub platform for creating interactive API documentation with try-it-now API explorer, auto-generated references from OpenAPI specs, custom landing pages, changelog, guides, and usage analytics. Features personalized docs that show API keys and example responses based on the logged-in user. Tracks which endpoints developers actually use. Integrates with GitHub for syncing docs from repos. Used by companies like Twilio and Shopify for their developer portals.

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.

Multi-agent model API that orchestrates frontier models behind one OpenAI-compatible endpoint

Sakana Fugu is a hosted model-provider API that exposes a learned multi-agent system as one OpenAI-compatible model. It dynamically routes coding, code review, research, and reasoning tasks across a frontier-model pool, with Fugu for lower-latency work and Fugu Ultra for harder workloads where answer quality matters more than cost or speed.

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.

API design and documentation standard

Industry-standard specification for defining RESTful APIs with a comprehensive ecosystem of tools. OpenAPI Specification (formerly Swagger) describes endpoints, parameters, responses, and authentication in YAML/JSON format. Swagger UI generates interactive API documentation, Swagger Editor provides a visual spec editor, and Swagger Codegen generates server stubs and client SDKs in 40+ languages. The foundation of API-first development workflows used by millions of developers worldwide.

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.

Official Python SDK for the xAI API

The xAI Python SDK is the official Python client for the xAI API, giving developers a direct way to build Grok-powered apps without relying on community proxies or unofficial wrappers. It supports synchronous and asynchronous Python clients for chat completions, streaming responses, function/tool calling, and multimodal workflows, making it a clean fit for backend services, agents, notebooks, and developer tools that need programmatic xAI access.