Are the audio files uploaded to convert them?

No. Conversion happens with ffmpeg compiled to WebAssembly, running inside this browser tab — files are never sent to a server.

Will converting a large batch be slow on a phone versus a desktop?

Each file in the queue is processed one at a time using the device's own CPU. A phone can handle typical song-length files fine, but a large batch of long recordings will finish much faster on a desktop browser with more memory and processing headroom.

Which formats can I actually encode to?

MP3 (libmp3lame), AAC/M4A, WAV (PCM), FLAC, OGG (Vorbis) and Opus are all supported — these match the codecs built into the default ffmpeg.wasm core.

Can I clean up background noise?

Yes — the noise reduction filter, noise gate and high-pass filter can all help with hiss, hum and room noise, though heavy noise reduction can be applied to real dialogue for the best results.

Can I add cover art to an MP3?

Yes, attaching a cover image is supported for MP3, M4A and FLAC output.

What does loudness normalisation do?

It targets a specific integrated loudness (LUFS) using the EBU R128 algorithm, so a batch of recordings ends up at a consistent perceived volume rather than wildly different peak levels.

ToolMano

Audio converter

Convert and compress audio between MP3, WAV, AAC, M4A, FLAC, OGG and Opus.

No uploadNo signupWorks offline

Drop files here or click to choose

MP3, WAV, AAC, M4A, FLAC, OGG or Opus · converted in your browser

Up to 20 MB · 3 files at a time

Output format

Bitrate (kbps)

Sample rate

Channels

Quick presets

Choose one or more audio files above to start.

Idle — nothing is uploaded, everything runs on this device.

Runs fully in this browser tab via WebAssembly — nothing is uploaded. Very large files are limited by your device's memory, roughly 2 GB in a browser tab, so trim long recordings first if you hit an out-of-memory error.

10 of 10 runs left today on the no-signup plan. Get more with a free account

About audio converter

Audio converter switches between MP3, WAV, AAC, M4A, FLAC, OGG and Opus, with deep control over bitrate, sample rate, bit depth, channels, loudness, equaliser bands, filters, noise gate, compressor, tempo/pitch and metadata — built for podcasters, musicians and anyone tidying up a batch of recordings.

A full seven-band equaliser, high-pass/low-pass/band-pass filters, a noise gate and a compressor sit alongside the format conversion, so a single pass can both change format and clean up a rough recording.

It processes files with ffmpeg.wasm directly in this browser tab and supports a batch queue, so several files can be converted with the same settings without uploading anything.

How to use Audio converter

1Drop in one or more audio files.
2Choose the output format, bitrate and channel layout, or pick a quick preset.
3Fine-tune EQ, filters, loudness, trimming and metadata tags in Advanced mode.
4Convert and download each file — batches are processed one after another.

What it does

MP3, WAV, AAC, M4A, FLAC, OGG and Opus in either direction
VBR/CBR bitrate control, sample rate, bit depth and mono/stereo/joint-stereo
Trim, fades, and automatic silence trimming or removal
Loudness normalisation to a target LUFS with true-peak and range control
Seven-band equaliser plus high-pass, low-pass and band-pass filters
Noise gate, basic noise reduction, de-esser and dynamics compressor
Tempo change with pitch preservation, and independent pitch shifting
Full metadata tagging with optional cover art, and a batch queue for multiple files

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