PLY, the Stanford triangle format, came out of 3D scanning, and it shows: it carries per-vertex extras like colour and confidence that most mesh formats have no room for. It exists as ASCII and binary; FileSorcery reads the ASCII form.
Every conversion below runs in this page, on your own machine. Nothing is uploaded, there is no queue, and there is no account to make. Pick a target format, or just drop a PLY file above and choose afterwards.