- [Fusio](http://www.fusio-project.org/) - Open-source API management platform which helps to build and manage REST APIs. ([Demo](http://fusio-project.org/demo), [Source Code](https://github.com/apioo/fusio)) `AGPL-3.0``PHP`
- [Hapttic](https://github.com/jsoendermann/hapttic) - Simple HTTP server that forwards all requests to a shell script to handle webhooks you receive. `Apache-2.0``Go`
- [Hasura](https://hasura.io) - Fast, instant realtime GraphQL APIs on Postgres with fine grained access control, also trigger webhooks on database events. ([Source Code](https://github.com/hasura/graphql-engine)) `Apache-2.0``Haskell`
- [Hoppscotch](https://hoppscotch.io) - A free, fast and beautiful API request builder. ([Demo](https://hoppscotch.io), [Source Code](https://github.com/hoppscotch/hoppscotch)) `MIT``Nodejs/Vue/Nuxt`
- [Kong](https://konghq.com/kong/) - The World’s Most Popular Open Source Microservice API Gateway and Platform. ([Source Code](https://github.com/Kong/kong)) `Apache-2.0``Lua`
- [KrakenD](https://www.krakend.io/) - Open source High-Performance API Gateway. ([Source Code](https://github.com/devopsfaith/krakend)) `Apache-2.0``Go`
- [Para](http://www.paraio.org) - Flexible and modular backend framework/server for object persistence, API development and authentication. ([Source Code](https://github.com/erudika/para)) `Apache-2.0``Java`
- [Postwoman](https://postwoman.io) - A free, fast and beautiful API request builder. ([Demo](https://postwoman.io), [Source Code](https://github.com/liyasthomas/postwoman)) `MIT``Nodejs/Vue/Nuxt`
- [Tyk](https://tyk.io) - Fast and scalable open source API Gateway. Out of the box, Tyk offers an API Management Platform with an API Gateway, API Analytics, Developer Portal and API Management Dashboard. ([Source Code](https://github.com/TykTechnologies/tyk)) `MPL-2.0``Go`