Add a Fade In and Fade Out to Audio

A hard cut at the start or end of a clip reads as unfinished. A fade smooths it. This is straightforward signal processing — a gain envelope applied sample by sample through the Web Audio API — which is exactly what a fade should be: precise, instant, and identical every time you run it. Set one fade for the whole batch and override individual files where they need something different; you can see the gain curve drawn over the waveform and hear the result before exporting. Equal-power curves avoid the loudness dip you get from a plain linear ramp, which matters when the fade is short. It sits alongside the AI tools on the same site, so a clip can be denoised, transcribed and faded without leaving the browser.

How to Add a Fade In and Fade Out to Audio

  1. 1

    Set the fade for every file

    Choose a fade-in and fade-out length, and pick a curve. Equal-power holds perceived loudness steady; linear is a straight ramp.

  2. 2

    Add your files

    Drop in a batch. Each file inherits the global fade until you say otherwise.

  3. 3

    Override individual files

    Select a file to see its waveform with the envelope drawn over it, then choose Customize this file to give it its own settings.

  4. 4

    Preview and export

    Play the faded result to check it by ear, then apply and download each file as a WAV.

How it works

A fade is pure signal processing. Each sample in the fade region is multiplied by a gain value derived from its position in the curve — linear gives a straight ramp, while equal-power uses a sine/cosine pair so that perceived loudness stays constant instead of dipping in the middle. The multiply happens sample by sample over the decoded buffer, so the output is sample-accurate and takes effectively no time regardless of file length. There is no model involved and there should not be: the correct answer here is a formula, and a formula is exact.

Supported formats

WAV, MP3, M4A, AAC, OGG and FLAC. Files are decoded by your browser, so anything it can play will work here. Output is exported as WAV.

Frequently asked questions

Is my audio uploaded anywhere?
No. Everything runs inside your browser using the Web Audio API, so the file never leaves your device. You can prove it: load the page, turn off your Wi-Fi, and the tool still works.
What is the difference between linear and equal-power?
A linear fade moves the amplitude in a straight line, which sounds like a dip in the middle because loudness is not linear. An equal-power curve compensates, keeping perceived volume steady through the fade. Equal-power is usually the better default.
Can I use different fades for different files?
Yes. Set a global fade for the batch, then override any individual file. Files you have not customised keep following the global setting when you change it.
Does this use AI?
No, and it should not. A fade is a gain curve — traditional DSP does it exactly, instantly, and the same way every time, which no model could improve on. The AI on Audio Magic is aimed at the problems rules cannot solve: Whisper for speech recognition and translation, and RNNoise or DeepFilterNet3 for separating a voice from background noise.
Do I need an account?
No. The free tools work straight away with no sign-up. Creating a free account raises your daily processing limit from 20 to 60 minutes.
Is it free?
Yes. Every tool on this page is free to use, with a daily limit on total audio processed. There is no watermark and no trial period.

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