Mono is a software platform designed to allow developers to easily create cross platform applications. It is an open source implementation of Microsoft's .NET Framework based on the ECMA standards for C# and the Common Language Runtime.

The Mono project is part of the .NET Foundation

[!IMPORTANT] The Mono Project (mono/mono) (‘original mono’) has been an important part of the .NET ecosystem since it was launched in 2001. Microsoft became the steward of the Mono Project when it acquired Xamarin in 2016.

The last major release of the Mono Project was in July 2019, with minor patch releases since that time. The last patch release was February 2024.

We are happy to announce that the WineHQ organization will be taking over as the stewards of the Mono Project upstream at wine-mono / Mono · GitLab (winehq.org). Source code in existing mono/mono and other repos will remain available, although repos may be archived. Binaries will remain available for up to four years.

Microsoft maintains a modern fork of Mono runtime in the dotnet/runtime repo and has been progressively moving workloads to that fork. That work is now complete, and we recommend that active Mono users and maintainers of Mono-based app frameworks migrate to .NET which includes work from this fork.

We want to recognize that the Mono Project was the first .NET implementation on Android, iOS, Linux, and other operating systems. The Mono Project was a trailblazer for the .NET platform across many operating systems. It helped make cross-platform .NET a reality and enabled .NET in many new places and we appreciate the work of those who came before us.

Thank you to all the Mono developers!

Join us on Discord in the #monovm channel:

Compilation and Installation
Using Mono
Directory Roadmap
Contributing to Mono
Reporting bugs
Configuration Options
Working with Submodules

Build Status

Public CI:

Legacy Jenkins CI (no longer available publicly):

| OS | Architecture | Status | |--------------|--------------------|------------------------------| | Debian 9 | amd64 | | | Debian 9 | i386 | | | Debian 9 | armel | | | Debian 9 | armhf | | | Debian 9 | arm64 | | | OS X | amd64 | | | OS X | i386 | | | Windows | amd64 | | | Windows | i386 | | | CentOS | s390x (cs) | | | Debian 9 | ppc64el (cs) | | | AIX 6.1 | ppc64 (cs) | | | FreeBSD 12 | amd64 (cs) | |

(cs) = community supported architecture

Compilation and Installation

Building the Software

Please see our guides for building Mono on Mac OS X, Linux and Windows.

Note that building from Git assumes that you already have Mono installed, so please download and install the latest Mono release before trying to build from Git. This is required because the Mono build relies on a working Mono C# compiler to compile itself (also known as bootstrapping).

If you don't have a working Mono installation

If you don't have a working Mono installation, you can try a slightly more risky approach: getting the latest version of the 'monolite' distribution, which contains just enough to run the 'mcs' compiler. You do this with:

# Run the following line after ./autogen.sh
make get-monolite-latest

This will download and place the files appropriately so that you can then just run:

make

The build will then use the files downloaded by make get-monolite-latest.

Testing and Installation

You can run the mono and mcs test suites with the command: make check.

Expect to find a few test suite failures. As a sanity check, you can compare the failures you got with https://jenkins.mono-project.com/.

You can now install mono with: make install

You can verify your installation by using the mono-test-install script, it can diagnose some common problems with Mono's install. Failure to follow these steps may result in a broken installation.

Using Mono

Once you have installed the software, you can run a few programs:

mono program.exe runtime engine
mcs program.cs C# compiler
monodis program.exe CIL Disassembler

See the man pages for mono(1), mcs(1) and monodis(1) for further details.

Directory Roadmap

acceptance-tests/ - Optional third party test suites used to validate Mono against a wider range of test cases.
data/ - Configuration files installed as part of the Mono runtime.
docs/ - Technical documents about the Mono runtime.
external/ - Git submodules for external libraries (Newtonsoft.Json, ikvm, etc).
ikvm-native/ - Glue code for ikvm.
libgc/ - The (deprecated) Boehm GC implementation.
llvm/ - Utility Makefiles for integrating the Mono LLVM fork.
m4/ - General utility Makefiles.
man/ - Manual pages for the various Mono commands and programs.
mcs/ - The class libraries, compiler and tools
- class/ - The class libraries (like System.*, Microsoft.Build, etc.)
- mcs/ - The Mono C# compiler written in C#
- tools/ - Tools like gacutil, ikdasm, mdoc, etc.
mono/ - The core of the Mono Runtime.
- arch/ - Architecture specific portions.
- benchmark/ - A collection of benchmarks.
- btls/ - Build files for the BTLS library which incorporates BoringSSL.
- cil/ - Common Intermediate Representation, XML definition of the CIL bytecodes.
- dis/ - CIL executable Disassembler.
- eglib/ - Independent implementation of the glib API.
- metadata/ - The object system and metadata reader.
- mini/ - The Just in Time Compiler.
- profiler/ - The profiler implementation.
- sgen/ - The SGen Garbage Collector implementation.
- tests/ - The main runtime tests.
- unit-tests/ - Additional runtime unit tests.
- utils/ - Utility functions used across the runtime codebase.
msvc/ - Logic for t

Mono

Install / Use

README

Contents