Fusio is an open source API management platform which helps to build and manage RESTful APIs. We think that there is a huge potential in the API economy. Whether you need an API to expose your business functionality, build micro services, develop SPAs or Mobile-Apps. Because of this we think that Fusio is a great tool to simplify building such APIs. More information on https://www.fusio-project.org/

Code Quality Rank: L4
Programming language: JavaScript
Tags: HTTP     API     Framework     REST     JavaScript     JSON     Swagger     OpenAPI    
Latest version: v1.9.0

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Fusio is an open source API management platform which helps to build and manage RESTful APIs. We think that there is a huge potential in the API economy. Whether you need an API to expose your business functionality, build micro services, develop SPAs or Mobile-Apps. Because of this we think that Fusio is a great tool to simplify building such APIs. More information on https://www.fusio-project.org/


The originally idea of Fusio was to provide a tool which lets you easily build a great API beside an existing application. I.e. in case you have already a web application on a domain acme.com Fusio helps you to build the fitting API at api.acme.com. Beside this use case you can also use Fusio to build a new API from scratch or use it internally i.e. for micro services.

To build the API Fusio can connect to many different databases, message queue systems or internal web services. There are also many ways to integrate your business logic into the API of Fusio.


Fusio covers all important aspects of the API lifecycle so you can concentrate on building the actual business logic of your API.

  • Versioning
    It is possible to define different versions of your endpoint. A concrete version can be requested through the Accept header i.e. application/vnd.acme.v1+json
  • Documentation
    Fusio generates automatically a documentation of the API endpoints based on the provided schema definitions.
  • Validation
    Fusio uses the standard JSONSchema to validate incoming request data
  • Authorization
    Fusio uses OAuth2 for API authorization. Each app can be limited to scopes to request only specific endpoints of the API.
  • Analytics
    Fusio monitors all API activities and shows them on a dashboard so you always know what is happening with your API.
  • Monetization
    Fusio provides a simple payment system to charge for specific routes.
  • Rate limiting
    It is possible to limit requests to a specific threshold.
  • Specification
    Fusio generates different specification formats for the defined API endpoints i.e. OpenAPI, Swagger, RAML.
  • Subscription
    Fusio contains a subscription layer which helps to build pub/sub for your API.
  • User management
    Fusio provides an API where new users can login or register a new account through GitHub, Google, Facebook or through normal email registration.
  • Logging
    All errors which occur in your endpoint are logged and are visible at the backend including all information from the request.
  • Connection
    Fusio provides an adapter system to connect to external services. By default we provide the HTTP and SQL connection type but there are many other types available i.e. MongoDB, Amqp, Cassandra.
  • Migration
    Fusio has a migration system which allows you to change the database schema on deployment.
  • Testing
    Fusio provides an api test case wherewith you can test every endpoint response without setting up a local web server.

Basically with Fusio you only have to define the schema (request/response) of your API endpoints and implement the business logic. All other aspects are covered by Fusio.


The basic building block of Fusio is the concept of an action. An action is simply a PHP class which receives a request and returns a response. Around this action Fusio handles all common logic like Authentication, Rate-Limiting, Schema validation, Logging etc. The class has to implement the following signature:


namespace App;

use Fusio\Engine\ActionAbstract;
use Fusio\Engine\ContextInterface;
use Fusio\Engine\ParametersInterface;
use Fusio\Engine\RequestInterface;

class HelloWorld extends ActionAbstract
    public function handle(RequestInterface $request, ParametersInterface $configuration, ContextInterface $context)
        return $this->response->build(200, [], [
            'hello' => 'world',

To give you a first overview, every request which arrives at such an action goes through the following lifecycle:


Fusio tries to assign the incoming request to a fitting route. The route contains all schema information about the incoming request and outgoing responses. Those schemas are also used at the documentation which is automatically available. If a request schema was provided the incoming request body gets validated after this schema. In case everything is ok the action which is assigned to the route gets executed.

An action represents the code which handles an incoming request and produces a response. Each action can use connections to accomplish this task. A connection uses a library which helps to work with a remote service. I.e. the SQL connection uses the Doctrine DBAL library to work with a database (it returns a Doctrine\DBAL\Connection instance). A connection always returns a fully configured object so you never have to deal with any credentials in an action. There are already many different actions available which you can use i.e. to create an API based on a database table.

With Fusio we want to remove as many layers as possible so that you can work in your action directly with a specific library. Because of this Fusio has no model or entity system like many other frameworks, instead we recommend to write plain SQL in case you work with a relational database. We think that building API endpoints based on models/entities limits the way how you would design a response. You only need to describe the request and response in the JSON schema format. This schema is then the contract of your API endpoint, how you produce this response technically is secondary. Fusio provides the mentioned connections, which help you to create complete customized responses based on complicated SQL queries, message queue inserts or multiple remote HTTP calls.


Fusio provides two ways to develop an API. The first way is to build API endpoints only through the backend interface by using all available actions. Through this you can solve already many tasks especially through the usage of the PHP-Sandbox or V8-Processor action.

The other way is to use the deploy mechanism. Through this you can use normal PHP files to implement your business logic and thus you can use the complete PHP ecosystem. Therefor you need to define a .fusio.yml deploy file which specifies the available routes and actions of the system. This file can be deployed with the following command:

php bin/fusio deploy

The action of each route contains the source which handles the business logic. This can be i.e. a php class, a simple php file or a url. More information in the [development doc](DEVELOPMENT.md). In the following an example action to build an API response from a database:


namespace App\Todo;

use Fusio\Engine\ActionAbstract;
use Fusio\Engine\ContextInterface;
use Fusio\Engine\ParametersInterface;
use Fusio\Engine\RequestInterface;

class Collection extends ActionAbstract
    public function handle(RequestInterface $request, ParametersInterface $configuration, ContextInterface $context)
        /** @var \Doctrine\DBAL\Connection $connection */
        $connection = $this->connector->getConnection('System');

        $count   = $connection->fetchColumn('SELECT COUNT(*) FROM app_todo');
        $entries = $connection->fetchAll('SELECT * FROM app_todo WHERE status = 1 ORDER BY insertDate DESC LIMIT 16');

        return $this->response->build(200, [], [
            'totalResults' => $count,
            'entry' => $entries,

In the code we get the System connection which returns a \Doctrine\DBAL\Connection instance but we have already many adapters to connect to different services. Then we simply fire some queries and return the response.


Fusio can be used in a lot of use cases. If you build an API based on entities which should be stored in a relational database you can use our code generator to simply build all routes, schemas and actions based on a simple YAML definition. The code can be used as great starting point to rapidly build your API. The tool is available at: https://generate.apioo.de/


Fusio provides several apps which work with the internal backend API. These apps can be used to manage and work with the API. This section gives a high level overview what the Fusio system provides and how the application is structured. Lets take a look at the components which are provided by Fusio:



If you install a Fusio system it setups the default API. Through the API it is possible to manage the complete system. Because of that Fusio has some reserved paths which are needed by the system.

  • /backend
    Endpoints for the system configuration
  • /consumer
    Endpoints for the consumer i.e. register new accounts or create new apps
  • /doc
    Endpoints for the documentation
  • /authorization
    Endpoints for the consumer to get i.e. information about the user itself and to revoke an obtained access token
  • /export
    Endpoints to export the documentation into other formats i.e. swagger

There is also a complete documentation about all internal API endpoints.




The backend app is the app where the administrator can configure the system. The app is located at /fusio/.


Fusio has a marketplace which contains a variety of apps for specific use cases. Every app can be directly installed from the backend app under System / Marketplace.


It is possible to install Fusio either through composer or manually file download. Place the project into the www directory of the web server.


composer create-project fusio/fusio




You can either manually install Fusio with the steps below or you can also use the browser based installer at public/install.php. Note because of security reasons it is highly recommended to remove the installer script after the installation.

  • Adjust the configuration file
    Open the file .env in the Fusio directory and change the key FUSIO_URL to the domain pointing to the public folder. Also insert the database credentials to the FUSIO_DB_* keys.
  • Execute the installation command
    The installation script inserts the Fusio database schema into the provided database. It can be executed with the following command php bin/fusio install.
  • Create administrator user
    After the installation is complete you have to create a new administrator account. Therefor you can use the following command php bin/fusio adduser. Choose as account type "Administrator".

You can verify the installation by visiting the FUSIO_URL with a browser. You should see a API response that the installation was successful. The backend is available at /fusio/.

In case you want to install Fusio on a specific database you need to adjust the driver parameter at the configuration.php file:

  • pdo_mysql: MySQL
  • pdo_sqlite: SQLite
  • pdo_pgsql: PostgreSQL
  • sqlsrv: Microsoft SQL Server
  • oci8: Oracle
  • sqlanywhere: SAP Sybase SQL Anywhere


Alternatively it is also possible to setup a Fusio system through docker. This has the advantage that you automatically get a complete running Fusio system without configuration. This is especially great for testing and evaluation. To setup the container you have to checkout the repository and run the following command:

docker-compose up -d

This builds the Fusio system with a predefined backend account. The credentials are taken from the env variables FUSIO_BACKEND_USER, FUSIO_BACKEND_EMAIL and FUSIO_BACKEND_PW in the docker-compose.yml. If you are planing to run the container on the internet you must change these credentials.


Here we list all available documentation resources. If these resources dont answer your questions or you want to provide feedback feel free to create an issue on GitHub.

Use cases

Today there are many use cases where you need a great documented REST API. In the following we list the most popular choices where Fusio comes in to play.

Business functionality

Exposing an API of your business functionality is a great way to extend your product. You enable customers to integrate it into other applications which gives the possibility to open up for new markets. With Fusio you can build such APIs and integrate them seamlessly into your product. We also see many companies which use the API itself as the core product.

Micro services

With Fusio you can simply build small micro services which solve a specific task in a complex system.

Javascript applications

Javascript frameworks like i.e. AngularJS or EmberJS becoming the standard. With Fusio you can easily build a backend for such applications. So you dont have to build the backend part by yourself.

Mobile apps

Almost all mobile apps need some form to interact with a remote service. This is mostly done through REST APIs. With Fusio you can easily build such APIs which then can also be used by other applications.


Contributions to the project are always appreciated. There are many options available to improve the project (which is not limited to coding). The following list shows some ways how you can participate:


If you are a PHP or Javascript developer you can help to improve the system. If you want to create a new feature it is in general recommended to create a new issue where we can talk about the feature before you start to hack on it. So there are three main components of Fusio:


The backend API is the core of the system developed in PHP, which provides the basic functionality of Fusio. This is the place to develop new core features and improvements.


An adapter is a plugin to the Fusio system which can be used to connect to other remote services. I.e. you could create a new adapter which speaks to a specific API or other remote service. This is easy to develop since you can build it in a separate repository. Please use the keyword fusio-adapter in your composer.json file so that adapter gets listed automatically on our website.


This is the AngularJS app which is used as GUI to control the backend. It is the main app to improve the Fusio backend. But you are also free to develop new apps for special use cases which talk to the internal API of Fusio.


In general we have a high PHPUnit test case coverage and also automatic end-to-end AngularJS tests using protractor and selenium. Beside this it is always great if users checkout the current master version of the project and try to test every aspect of the system. In case you have found an issue please report it through the issue tracker.


We want to create a sytem which is easy to use also by novice users. To enable everybody to start using Fusio we need a simple to understand documentation. Since we have not always the view of a novice developer please let us know about chapters which are difficult to understand or topics which are missing. You can also send us directly a pull request with an improved version. The main documentation of Fusio is available at readthedocs. The documentation source is available in the docs/ folder.



If you are a blogger or magazine we would be happy if you like to cover Fusio. Please take a look at the Media section of our About Page to download the official icon set. In case you have any questions please write us a message directly so we can help you to create great content.


If you are a company or freelancer and want to get detailed information how you can use Fusio you can contact us for consulting. In the workshop we try to find the best way how you can use/integrate Fusio also we try to explain the functionality and answer your questions.


If this project helps you to generate revenue or in general if you like to support the project you can donate any amount through paypal. We like to thank every user who has donated to the project.