Welcome to the Guido project
Grame - Centre National de Création Musicale
The Guido project is an open source project that encompasses a music notation format, a score rendering engine and various music score utilities. The Guido Notation Format is a general purpose formal language for representing score-level music in a platform-independent plain text and human readable way. The format comes with various software components for music score rendering and manipulation. The main of these components is the Guido Engine, a library embedable in various platforms and using different programming languages.
The Guido engine runs on the main operating systems: Linux, MacOS, iOS, Windows, Android.
See the Guido page for more information.
See the Guido documentation for the Guido language documentation.
See the Guido online editor to test the system.
See the Guido wiki for building instructions.
Build status : 
Acknowledgments
The Guido project has been initiated in the 90s by Holger Hoos, Jürgen Kilian and Kai Renz, who designed the Guido Music Notation format and developed the core of the Guido engine. It became an open source project on 2002 at Grame initiative.
I would like to thank all the people who have been contributing to the project, and especially:
J. Scott Amort, Jérôme Berthet, Samuel Brochot, Yannick Chapuis, Michael Chourdakis, Thomas Coffy, Christophe Daudin, Colas Decron, Guillaume Gouilloux, Torben Hohn, Camille Le Roy, François Levy, Arnaud Margaillan, Benjamen Ruprechter, Mike Solomon, Ivan Vukosav
And of course, warmest thanks to my colleagues and friends Stéphane Letz and Yann Orlarey.