The GUIDO project gathers a textual format for music representation, a rendering engine operating on this format, and a library providing a high level support for all the services related to the GUIDO format and it's graphic rendering. The project includes now an HTTP server that allows users to access the musical-score-related functions in the API of the GUIDOEngine library via uniform resource identifiers (URIs). This article resumes the core tenants of the REST architecture on which the GUIDO server is based, going on to explain how the server ports a C/C++ API to the web. It concludes with several examples as well as a discussion of how the REST architecture is well suited to a web-API that serves as a wrapper for another API.