PDFCrowd - Pdfcrowd is a Web/HTML to PDF online service. Convert HTML to PDF online in the browser or in your PHP, Python, Ruby, .NET, Java apps via the REST API.
Captain Chords - Write chord progressions in your favorite DAW
DocRaptor - As the only API powered by the Prince HTML-to-PDF engine, DocRaptor provides the best support for complex PDFs with powerful support for headers, page breaks, page numbers, flexbox, watermarks, accessible PDFs, and much more
Odesi - ODESI is a music sketchpad that exports your projects to Audio and MIDI.
PDFShift - Convert any HTML documents to high-fidelity PDF using a single POST request
Cthulhu - VST MIDI-FX plugin for harmonic inspiration