AudioAdjustable qualityRuns in your browser

Volume Booster

Make a quiet recording louder — or a loud one quieter — and add a fade in or out. Some detail is discarded to fit the target format; how much depends on the format and your settings.

Not uploaded to any serverConverted on this deviceGone when you close the tabHow this works

Drop your files here

MP3, WAV, FLAC, AAC and 5 more formats · up to 300 MB each

or paste files from your clipboard

Ready when you are

Make a quiet recording louder — or a loud one quieter — and add a fade in or out. Everything happens in this tab; nothing is sent anywhere.

⌘K to search converters

How to use it

1
Add your files
Volume Booster works with MP3, WAV, FLAC, AAC, M4A, OGG, Opus, AIFF and WMA. Drop them in, browse for them, or paste from your clipboard.
2
Choose your options
Tune bitrate, sample rate and channels — or leave the defaults, which are sensible.
3
Run it and download
Press the button and save the result. Everything happens on your device, and nothing is uploaded.

Privacy, in plain words

Is it safe? Your audio file is not uploaded anywhere

What “uploaded” normally means. On most online converters, pressing the button copies your file across the internet onto a computer owned by that website. That copy is what the word “upload” means, and it is the part nobody explains.

What happens instead. This site does not do it. There is no server here that receives files, so your audio file is read, converted and handed back by the browser you are using right now. It never travels — so there is no copy to store, read, leak or hand over.

Check it yourself in ten seconds

Turn off your Wi-Fi after this page has loaded, then convert a file anyway. It still works, because everything needed is already on your device.

The longer explanation of how this works, and the full detail of what is and is not stored on the privacy page.

Why this matters more than it sounds

An audio file is a conversation. Transcribed by machine — which is cheap now — it becomes searchable text about whoever was speaking. It matters more than it sounds, because of what audio files usually are:

Interviews

a source's voice is identifying even when the name is not said

Voice notes and dictation

thinking out loud, never meant for an audience

Therapy and consultation recordings

clinical material with strict handling rules

Meeting audio

internal discussion, named people, unannounced decisions

A file that is never sent cannot be kept, leaked, subpoenaed or used to train anything. That is a property of how this works, not a promise about how carefully it is run.

Louder without the crackle

Raising the volume multiplies every sample by the same amount. Measured in decibels, +6 dB doubles the signal's power and +10 dB is roughly what people hear as twice as loud. The quiet parts come up, and so do the loud parts — which is where a naive boost goes wrong.

Digital audio has a hard ceiling. A peak pushed past it is cut flat, and a flattened peak is the crackle you hear from a phone speaker played too loud. Every boost here runs through a limiter that catches those peaks and holds them just under the ceiling, so the body of the recording gets louder while the transients are tamed rather than clipped.

Boost versus normalise: A boost adds a fixed amount. Normalising measures the whole recording and sets it to a standard loudness. Boost when one file is simply too quiet; normalise when several files need to match.
Fades are measured on the result: A five-second fade out ends exactly where the file does, and a fade can never be longer than half the recording, so a short clip is never faded from start to finish.
It cannot add detail: Hiss, room noise and distortion captured in the recording come up with everything else. A boost makes a quiet recording audible, not cleaner.

About these formats

Accepts

MPEG-1 Audio Layer III

The universal lossy audio format.

Extensions: .mp3
MIME type: audio/mpeg
Best for: Music players · Podcasts · Maximum compatibility
Compatibility: Plays absolutely everywhere.

Accepts

Waveform Audio

Uncompressed PCM audio. Perfect quality, big files.

Extensions: .wav, .wave
MIME type: audio/wav
Best for: Editing and mastering · Sound design · Archival
Compatibility: Universal.

Boosts go through a limiter, so peaks are held just under full scale instead of crackling.

Good to know

Volume Booster — questions

How does Volume Booster work?

Make a quiet recording louder — or a loud one quieter — and add a fade in or out. Add your files above, adjust anything you want to change, and press the button. The result downloads straight to your device.

Is there anything I should watch out for?

Boosts go through a limiter, so peaks are held just under full scale instead of crackling.

Is Volume Booster safe — are my files uploaded to a server?

No, nothing is uploaded. On most online tools, pressing the button copies your file across the internet onto a computer owned by that website, where it is processed and then sent back. That copy is what "upload" means. This tool does not do it: your file is read and processed by the browser you are using right now, stays on this device the whole time, and is discarded when you close the tab. Turn off your Wi-Fi after the page loads and it still works, which is the quickest way to confirm it.

Can I use this on confidential or personal documents?

Yes — that is the case it was built for. Because the file never leaves your device, a confidential document is no more exposed than it is sitting in your own folder: there is no transfer, no copy on anybody else's hardware, no retention period and no staff with access. Nothing about the file is logged either — not its name, not its size, not its contents.