Upload a M4A file and get a OGG back. No signup, no watermark, no limit on how many.
M4A is an MPEG-4 container holding AAC audio — the same codec as a bare .aac file, wrapped so that players, tags and cover art all behave.
Where you run into it: iTunes and Apple Music purchases, voice memos, Zoom and Teams recordings, most phone-recorded audio.
What it costs you: Outside Apple's ecosystem support is good but not universal, and a few older tools still refuse the extension on sight.
OGG here means Vorbis audio in an Ogg container — a patent-free lossy codec that generally beats MP3 at the same bitrate.
Where you run into it: Game audio, Wikipedia and Wikimedia files, Spotify's streaming internals, Linux desktops.
What it costs you: Technical merit never bought it consumer support: plenty of car stereos and older phones simply do not list it.
The AAC inside your .m4a is decoded and re-encoded as Vorbis, two codecs that share no structure, so the audio is rebuilt rather than repackaged and you spend one generation doing it. They are close in efficiency, so Best quality or 192 kbps lands you somewhere very near where you started. What changes is licensing and support: Vorbis in an Ogg container is the format that open-source audio tooling reaches for first, and a good deal of it will not open an .m4a at all.
The common case here is a voice recording. iPhone Voice Memos, WhatsApp notes and most Android recorders all write AAC in an .m4a, and the places people want to take them — Audacity on Linux, a Godot or Unity project, a Telegram bot, an archive that insists on open formats — prefer Ogg. Two practical notes for that case: these recordings are usually mono and already modest, so there is nothing to gain from 320 kbps, and if you only need the audio to edit, converting once at Best quality and working from that beats converting repeatedly.
Yes, entirely, and there is no cap on how many files you convert. No account, no watermark, no trial.
A little, as with any second encode. The two codecs are similar enough in efficiency that a generous setting keeps the difference below the threshold of a normal listen. The exception is speech recorded at a low bitrate, where the first encoder already stripped the file thin and the second has little room left to be careful with.
Similar at matched quality, because neither codec has a decisive efficiency advantage over the other at these bitrates. Do not expect the conversion to save space; if the Ogg is much smaller, you picked a bitrate below what the .m4a was carrying.
Yes — OGG is one of the formats this converter writes, so the reverse page exists at /ogg-to-m4a/. Both formats are lossy, so every leg re-encodes: going out and coming back costs two more generations, and the damage accumulates.
The file is uploaded to do the conversion — nothing here runs in your browser — and both your upload and the converted result are deleted the moment the file is sent back. Nothing is stored and nothing is logged beyond the request itself.