The initial use case of Fusio was to be able to quickly create a great API product beside an existing web app. We have many users which run a traditional/legacy web app and they use Fusio to create a state-of-the-art API beside there existing product. Fusio provides many ways to make your business logic available as API.
Fusio provides a developer app which helps to on board new users to use your API. It is also possible to completely integrate Fusio into your existing product since the app also only works with the internal Fusio API.
You can use Fusio as API-Gateway. In this case Fusio acts as the single entrypoint for all your internal APIs / microservices. Through this you get a complete overview about your API landscape and you can cover topics like authorization, rate limiting and monetization.
Fusio contains also a schema store which then contains all schema data for each request and response. Based on these schemas Fusio can automatically generate an OpenAPI specification or also client SDKs.
You can use Fusio as backend to build SPAs using popular Javascript-Frameworks like i.e. Angular, React or Vue. Fusio is really great as backend for those frontend frameworks since it is possible to automatically generate a complete type-safe javascript client SDK which can be directly used at those frontends.
In this sense Fusio can be seen as a self-hosted alternative solution to services like Firebase or Supabase.
You can use Fusio as API Builder, this means you can automatically generate complete REST APIs based on different data sources i.e. relational databases (MySQL, Postgres), No-SQL (MongoDB, Elasticsearch) or also the file system to expose files.
Through this you can rapidly build REST APIs and it is also possible to extend all endpoints with custom logic.
You can use Fusio also simply as framework to build an API from scratch. In this case you can develop custom actions and use the deploy mechanism. Please take a look at our sample headless CMS which shows how to build and structure a complex app using Fusio.