API Client Development Tools

.Dart

• Frog
• Serverpod - generation app and web server, built for the Flutter community. It allows you to write your server-side code in Dart, automatically generate your APIs, and hook up your database with minimal effort. Serverpod is open-source, and you can host your server anywhere.

General

• at-your-service
• Swagger CodeGen - compliant server.
• AutoRest
• OpenAPI Generator

Java

• Retrofit - safe HTTP client for Android and Java.

Javascript

• Restangular

.NET

• Refit - safe REST library for .NET Core, Xamarin and .NET
• WebAnchor - safe, testable and flexible access to web resources.

Ruby

• Net::HTTP
• faraday
• rest-client
• heroics
• blanket
• nestful

API Clients

Desktop

• Firecamp
• Paw
• Insomnia
• Firecamp
• httpy
• HTTPie

Hosted

• JSON Generator

Open Source

• Hoppscotch
• Hurl
• ATAC - full TUI API client made in Rust. ATAC is free, open-source, offline and account-less.

API Debugging and Mocking

Desktop

• Mockoon
• Json-Server

Hosted

• MockBin
• MockingCloud
• Svix Play
• httpbin
• Prism
• MockBin

API Design Guides

Desktop

• PayPal API Style Guide
• Haufe API Style Guide
• Microsoft REST API Guidelines
• The RESTed NARWHL
• Zalando REST API Guidelines
• API Stylebook Design Guidelines
• API Stylebook Design Topics
• Azure API Design
• Heroku Platform HTTP API Design Guide
• Haufe API Style Guide
• 18F API Standards
• White House Web API Standards
• API Stylebook Design Guidelines
• The RESTed NARWHL

API Developer Portal

Desktop

• Tyk
• APIMATIC - tailored for your API.
• Optic Docs - accurate OpenAPI documentation with your consumers. With Optic they can subscribe to your API and get notified when it changes.
• Optic Docs - accurate OpenAPI documentation with your consumers. With Optic they can subscribe to your API and get notified when it changes.

API Documentation

.Dart

• DeveloperHub - facing API docs.
• Apiary
• API Docs
• ReDoc - generated API Reference Documentation.
• Swagger UI - compliant API.
• Slate
• prmd
• Aglio
• Docbox
• widdershins
• Elements - based API documentation for OpenAPI 3.x/2.x

API Frameworks

C#

• ASP.NET Web APIs

Elixir

• Plug

Erlang

• Cowboy
• Gen Microservice
• Mochiweb

Go

• Go-Json-Rest
• gocrud
• sleepy - framework written in Go.
• restit
• go-rest
• go-restful
• Goat
• Resoursea
• Fiber
• go-relax
• Zerver

Haskell

• Scotty
• Spock
• Servant - Level Web DSL.
• Yesod

Java

• Dropwizard - friendly, high-performance, RESTful web services.
• Jersey
• Metamug Mason
• Rest.li - safe bindings and asynchronous, non-blocking IO.

Javascript

• Express
• sailsjs
• Actionhero - transport Node.js API server with integrated cluster capabilities and delayed tasks.
• Seneca
• Feathers - time APIs through Socket.io or Primus.
• Restify
• Deployd
• Seneca

Miscellaneous

• Dream Factory

MySQL

• xmysql

PHP

• API Platform - LD, Schema.org and Hydra support
• Dingo API
• Fractal
• Yii2 Framework

Postgres

• pREST
• PostgREST

Python

• Tastypie
• restless
• flask-restful
• Falcon - level, high-performance Python framework for building HTTP APIs, app backends, and higher-level frameworks.
• apistar
• sanic - like Python 3.5+ web server that's written to go fast.
• hug
• FastAPI - performance), web framework for building APIs with Python 3.6+ based on standard Python type hints.
• Connexion

R

• Plumber

Ruby

• rails-api
• pliny
• grape - framework for creating REST-like APIs in Ruby.
• ActiveModel::Serializer
• rabl
• jbuilder - style DSL.
• roar

Scala

• Play
• Spray - source toolkit for building REST/HTTP-based integration layers on top of Scala and Akka.
• Colossus
• Finatra - Server and Finagle.
• Skinny Micro - web framework to build servlet applications in Scala.
• Akka HTTP - and client-side HTTP stack on top of akka-actor and akka-stream.
• Swagger Akka HTTP - Akka-Http brings Swagger support for Akka-Http Apis.

API Gateways

Desktop

• AWS API Gateway
• Ambassador API Gateway - performance Envoy Proxy.
• Apigee127
• Pushpin
• Camel - specific languages, including a Java-based fluent API, Spring or Blueprint XML configuration files, and a Scala DSL.
• HAProxy
• OpenResty
• Tyk - source, fast and scalable API gateway, portal and API management platform.
• Kong - source management layer for APIs, delivering high performance and reliability.
• APIGrove
• APISIX - Native API gateway, based on the Nginx library and etcd.
• Strongloop
• Vulcand
• Zuul
• fabio - conf load balancing HTTP(S) router for deploying microservices managed by consul by eBay.
• Traefik
• Oathkeeper
• Zuplo - Powered API Management platform for API Development, Deployment, and Documentation. Add auth, rate-limiting, and monetization to your API in minutes.
• Kong - source management layer for APIs, delivering high performance and reliability.
• Pushpin
• Fusio

API Monitoring

Desktop

• Runscope
• Ping-API

API Security

Desktop

• Online OpenAPI/Swagger File Security Audit
• API Security checklist
• Ory Hydra

API Specification Languages

• RAML
• OpenAPI (formerly known as Swagger)
• API Blueprint

API Specifications

• API Commons - agnostic API specifications / Data Models.
• API Commons - agnostic API specifications / Data Models.
• APIS.guru

API Specification Tools

• Swagger Inspector - generate OpenAPI documentation for any API.
• Swagger Editor
• Swagger Tools and Integrations
• OpenAPI extension for VS Code
• OpenAPI plugin for JetBrains IDEs
• Apimatic
• OpenAPI Definition Designer
• Stoplight Studio
• Optic - to-date
• Swagger Inspector - generate OpenAPI documentation for any API.
• Dredd
• API Spec Converter
• Spectral
• Optic - to-date
• RateMyOpenAPI - source tools that scans your OpenAPI spec and identifies issues with documentation, security, and SDK generation - and generates a report with fix suggestions.
• OpenAPI DevTools
• Swagger Editor
• Swagger Editor

API Testing

Desktop

• Optic CI
• Pyresttest
• OWASP Zaproxy
• RestQA

API Web Scanners

Desktop

• Cherrybomb - done API specifications! Cherrybomb is a CLI tool that helps you avoid undefined user behaviour by validating your API specifications.

Contributing

Desktop

• Pull Requests

JSON Format Standards

Desktop

• HAL
• JSONAPI
• Hydra
• JSON-LD
• Ion
• HAL
• JSONAPI

Learning Resources

Desktop

• REST in Practice
• Roy Fielding's dissertation on REST
• Automated API Development
• Nordic APIs
• Undisturbed REST
• Build APIs You Won't Hate
• Irresistible APIs
• How to build an API
• API University
• RESTful Web Services