Two formats. Two different jobs. Masterd converts uploaded WAV, MP3, and M4A files only.
WAV — for production
WAV is larger and uncompressed, making it better for editing, sessions, stems, and keeping a high-quality working copy.
MP3 — for sharing
MP3 is smaller and easier to send, upload, and play nearly anywhere — demos, group chats, and quick uploads.
Converting between them
WAV to MP3 is a good move when you need a smaller file. MP3 to WAV can help compatibility, but it does not restore lost audio quality.