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Saturn is a web development framework written in F# which implements the server-side MVC pattern. Many of its components and concepts will seem familiar to those of us with experience in other web frameworks like Ruby on Rails or Python’s Django.

It's heavily inspired by Elixir's Phoenix.

Read more about why I've decided to create Saturn, and some of its design choices on my blog -

Saturn rings

Saturn itself is top layer of a multi layer system designed to create flexible, productive environment for creating web applications.

Kestrel and ASP.NET Core

ASP.NET Core is a cross-platform, high-performance, open-source framework for building modern, cloud-based, Internet-connected application

Kestrel is a cross-platform web server for ASP.NET Core based on libuv, a cross-platform asynchronous I/O library


Giraffe is an F# micro web framework for building rich web applications. It has been heavily inspired and is similar to Suave, but has been specifically designed with ASP.NET Core in mind and can be plugged into the ASP.NET Core pipeline via middleware. Giraffe applications are composed of so called HttpHandler functions which can be thought of a mixture of Suave's WebParts and ASP.NET Core's middleware.

Saturn moons

Saturn is not only a library building on top of Giraffe, but also set of opinionated tooling for scaffolding a whole project and then generating some boilerplate code. At the moment our template is using (by default):


a simple, focused on performance object mapper for .Net that you can add in to your project that will extend your IDbConnection interface.


Simple.Migrations is a simple bare-bones migration framework for .NET Core (.NET Standard 1.2 and .NET 4.5). It doesn't provide SQL generation, or an out-of-the-box command-line tool, or other fancy features. It does however provide a set of simple, extendable, and composable tools for integrating migrations into your application.


Built on top of the battle-tested ASP.NET Core foundation, a highly flexible, extendable model of Giraffe Saturn provides high level abstractions, helpers and tools to enable high developer productivity, at the same time keeping high application performance provided by Kestrel and Giraffe.

Saturn is made up of a number of distinct parts, each with its own purpose and role to play in building a web application.

  • Application
    • the start and end of the request lifecycle
    • handles all aspects of requests up until the point where the router takes over
    • provides a core set of plugs to apply to all requests
    • dispatches requests into a router
    • enables application and hosting configuration
  • Router
    • parses incoming requests and dispatches them to the correct controller/action, passing parameters as needed
    • provides helpers to generate route paths or urls to resources
    • defines named pipelines through which we may pass our requests
    • allow easy application of groups of plugs to a set of routes
  • Controllers
    • provide functions, called actions, to handle requests
    • actions:
      • prepare data and pass it into views
      • invoke rendering via views
      • perform redirects
      • returns data as JSON or XML
      • and much more
  • Views
    • render templates
    • act as a presentation layer
    • define helper functions, available in templates, to decorate data for presentation
  • Channels [Not implemented yet]
    • manage sockets for easy realtime communication
    • are analogous to controllers except that they allow bi-directional communication with persistent connections
  • Scaffolding scripts

How to contribute

Imposter syndrome disclaimer: I want your help. No really, I do.

There might be a little voice inside that tells you you're not ready; that you need to do one more tutorial, or learn another framework, or write a few more blog posts before you can help me with this project.

I assure you, that's not the case.

This project has some clear Contribution Guidelines and expectations that you can read here.

The contribution guidelines outline the process that you'll need to follow to get a patch merged. By making expectations and process explicit, I hope it will make it easier for you to contribute.

And you don't just have to write code. You can help out by writing documentation, tests, or even by giving feedback about this work. (And yes, that includes giving feedback about the contribution guidelines.)

Thank you for contributing!

The project is hosted on GitHub where you can report issues, fork the project and submit pull requests.

The library is available under MIT license, which allows modification and redistribution for both commercial and non-commercial purposes.