Free online tool

Batch Audio Editor Online

Batch process audio in your browser: apply one speed change, bass boost, reverb or width setting to many files and export a ZIP of MP3s. Free, no upload.

Open the free editor: upload MP3, WAV, AAC, OGG or FLAC, adjust speed, reverb, bass, tone, width and space, then export MP3 or a ZIP of many tracks. Everything runs in your browser.

A batch audio editor applies one edit to many files without making you open each file, change it and save it by hand. The editor above does exactly that in the browser: load as many audio files as you want, select them, move a slider, and every selected file picks up the change. Then one click gives you a ZIP of finished MP3s.

Most people arrive here for the slowed + reverb sound, and the bulk slowed reverb page is written for them. This page is about everything else you can batch with the same six controls. A batch bass boost for a set of beats. A batch speed change for a pile of voice recordings. A batch reverb pass over a folder of dry vocal stems. A batch mono fold for files that need to play on a single speaker. The bass booster and speed up pages explain each control on its own; here the point is doing it to twenty files at once.

The processing chain is fixed and small. You get Speed, Reverb with a Space decay control, Bass and Tone shelves, Width, and a Preserve pitch switch. You do not get a multiband EQ, a compressor, a normaliser or a trimmer. If your batch job fits within those six controls, this is the fastest free way to do it, because there is no upload step and no per-file waiting on a server.

What batch processing means here

The track list is the batch. Every file you add becomes a row. Selection decides which rows a slider move affects.

• Select All Tracks turns the sliders into a global effect. Change Bass and every file gets the same Bass.
• Clear Selection then clicking individual tracks makes a subset. Only those tracks change.
• Download Selected exports the subset as selected-remixes.zip. Download All exports everything as all-remixes.zip. Each MP3 inside is named after the source file with -remix appended.
• Delete Selected and Delete All clear the list when you move to the next job.

Because selection is the only mechanism, you can run several different batch jobs from one loaded list. Boost bass on all the beats, select only the two vocal files and add reverb to those, then download everything together.

Batch jobs this editor handles well

Each row is a separate job you might run on a different folder, and each only needs one or two sliders. The rest stay at their Dry values.

Worked examples

A beat tape needs more weight. Load all twelve beats. Select All Tracks. Set Bass to +6 dB and Tone to -2 dB, leave Speed at 1.00x and Reverb at 0. Play the beat with the most sub already in it. If it buzzes on your phone, pull Bass back to +4 for that one track as a subset. Download All.

A semester of lecture recordings is too slow. Load the recordings. Select All Tracks. Turn Preserve pitch on so voices stay natural, then set Speed to 1.25x. The pitch stays put and only the pace changes. Nothing else needs to move. Download All, and the ZIP holds every lecture at a quarter faster. One caveat: Preserve pitch changes the live preview only; exported files keep the speed-linked pitch, so the voices in the ZIP will sit higher. For in-key files, use Audacity's Change Tempo. The preserve pitch page explains what the time-stretch does and where it starts to warble.

A folder of dry vocal takes needs a shared room. Select All Tracks, set Reverb to 30% and Space to 2.2 s. That is a small, consistent room on every take. Leave Speed at 1.00x so the takes still line up with the instrumental they were recorded to.

Old low-quality rips sound harsh. Select All Tracks and set Tone to -4 dB. If they also feel thin, add Bass at +3 dB. This will not repair compression artifacts, but it hides the worst of the top-end fizz.

Speed changes with and without pitch

The Speed control is the one most likely to be misused in a batch, so it is worth being precise. With Preserve pitch off, speed and pitch are locked together, the way a record player works. 1.19x is roughly three semitones up, 0.84x roughly three semitones down. That is the right behaviour for music edits where the pitch shift is part of the sound.

With Preserve pitch on, the editor time-stretches instead, so the tempo changes and the key does not. That is what you want for speech, practice tracks and anything where a shifted voice would sound wrong. The time-stretch is done by the browser and can add a slight warble at extreme settings, so keep speech between 0.80x and 1.40x for clean results.

Export, honestly

Every batch export is MP3 at 96 kbps, 32 kHz, encoded in a web worker so the page stays usable while it runs. There is no WAV, FLAC or high-bitrate MP3 option. That makes this editor the wrong tool for archival work or for mastering a release. It makes it the right tool for anything that ends up on YouTube, TikTok, Shorts, a podcast host or a phone, because those destinations re-encode the audio anyway and 96 kbps is already above what many of them deliver to listeners.

Speech, which is most of the non-music batch work people bring here, survives 96 kbps with no trouble at all. Dense music with lots of cymbals is where the ceiling shows. If that matters for your job, process a WAV source and finish in a DAW.

How long a batch takes

The render runs faster than real time, and each track is encoded in turn. A laptop handles a long list without complaint. A phone takes noticeably longer per track and can pause the job if the screen locks or you switch apps, so on mobile keep the tab in front and process in smaller groups. The work is identical on every device; only the wait is different.

Memory is the other constraint. Each loaded file is held as decoded, uncompressed audio. Long WAV files in large numbers can push a tab toward its memory limit. Clear files you have already exported with Delete Selected before loading the next group.

When a DAW is the better batch tool

Be clear about the boundary. If your batch needs loudness normalisation, trimming silence, fades, format conversion to WAV, a limiter, or a multiband EQ, this editor cannot do it and a DAW or a command line tool like ffmpeg can. The online vs DAW comparison lays out that trade. What the browser editor offers instead is zero setup, zero upload and a workflow that a non-producer can learn in a minute.