Audio Converter
betaConvert MP3, WAV, FLAC, AAC and Opus in your browser — with bitrate, trim, normalise and tag options
How it works
Drop audio or video files and pick an output: MP3 (via a WebAssembly LAME encoder), AAC in M4A or ADTS, Opus in Ogg or WebM, FLAC, or WAV at 16/24-bit or 32-bit float. The file is demuxed and decoded locally, optionally resampled and remixed to mono or stereo, trimmed to a start/end time, gain-adjusted or peak-normalised to −1 dBFS, then encoded with the browser's WebCodecs — nothing leaves your device. Tags (title, artist, album, cover art) are carried over, edited, or stripped. Formats the current browser can't encode are greyed out; Chrome and Edge support the full set.
Questions
Which formats can I convert between?
Input: anything the browser can demux — MP3, WAV, FLAC, AAC/M4A, Ogg Vorbis/Opus, WebM, MP4/MOV/MKV video (the audio track is extracted). Output: MP3, AAC (M4A or raw ADTS), Opus (Ogg or WebM), FLAC and WAV.
Is the conversion lossless?
WAV and FLAC are lossless. MP3, AAC and Opus are lossy; converting one lossy format to another always loses a little more, so keep the bitrate at or above the source's.
Are my files uploaded?
No. Decoding and encoding run in your browser with WebCodecs and a WASM MP3 encoder. Large files work, limited only by your device's memory.
Why is a format greyed out?
Encoders come from the browser. Safari and Firefox lack some WebCodecs audio encoders (AAC, FLAC or Opus depending on the version); MP3 and WAV work everywhere because they don't rely on the browser.
Can it normalise loudness?
It peak-normalises to −1 dBFS (a measuring pass followed by the encode) and applies a manual gain in dB. LUFS loudness normalisation isn't included.