How to convert .gp3 files directly to .mp3 format.
Converting Guitar Pro 3 Tablatures directly to MP3 Audio Files (.gp3 to .mp3 conversion) is certainly possible and quite straightforward, even though your options are somewhat limited.
Use the latest version of Guitar Pro, which allows users to import GP3 tablatures and export them in MP3 format.
A multi-track editor and music composer for guitars
A free cross-platform music notation software