BrowserTools

Audio Reverser

Play any audio backwards

By Guga — BrowserTools maintainer, Tbilisi, Georgia Updated 2026-09-14
Free Private No uploads

Reversing buffers the whole decoded signal in memory, and the WebAssembly FFmpeg core that decodes it — about 30 MB — is downloaded from unpkg.com on your first run here. Your recording is not uploaded.

What is Audio Reverser?

The whole signal is turned around: the last sample becomes the first, and playback runs backwards from there. It is a time-domain reversal, not a filter sweep, so every transient is inverted along with everything else — reversed speech is genuinely unintelligible rather than merely strange. There is a caveat worth knowing if you are hunting for a hidden message: modern lossy encoders smear sharp transients across neighbouring frames, so reversing an AAC or MP3 recording rarely reveals a clean phrase that was there in the studio. Working from a WAV or FLAC source gives you a far better chance. The engine also has to hold the entire decoded signal in memory while it reverses, so length costs RAM.

Reverse an audio file so it plays backwards — the classic technique for hidden-message hunting, sound design and music production effects. Runs locally in your browser.

Private Audio Reverser In Your Browser

Audio Reverser is processed locally with client-side JavaScript. Your files never touch a server, and there is no queue to wait in.

Step-by-Step

How to use Audio Reverser

1

Feed in a recording — MP3, WAV, OGG, M4A, FLAC, or just the audio side of a video.

2

Press Reverse audio — the areverse filter buffers the decoded track, so the wait scales with duration and memory.

3

Allow for the one-time engine download the first time you use this page; after that the reversal itself is the only delay.

4

Play the result in the audio player, then use the Download MP3 button to keep it.

Key Capabilities
  • Applies a true time-domain reversal to every sample, not an approximation or a fade trick.
  • Accepts video files and reverses only their audio track, discarding the picture.
  • Writes the reversed result as a standard MP3 at variable bitrate quality level 2.
  • Requires no plugin and no manual sample editing — one filter in one pass.
Common Use Cases
  • A producer layering a reversed cymbal swell under a drum fill to build a transition.
  • A sound designer testing whether an odd artefact in a mix is a reversed layer left in by mistake.
  • A musician checking a chorus vocal by ear for a deliberately backwards line someone added.
Clear Answers

Frequently Asked Questions

Why did reversing a 4-minute track take so long?
The reversal needs the whole decoded signal in memory before it can write a single output sample. Four minutes of 44.1 kHz stereo 16-bit audio is around 42 MB of raw samples, and the engine holds that plus the output buffer while working. Reversing a long file is inherently memory-bound.
Why can I never hear a hidden message, even reversed?
Almost always because of the source format. Lossy audio encoders cannot preserve a sharp transient within a single frame, so anything said over a reversed backwards word is smeared into noise. A WAV or FLAC master, or a cassette transfer, gives the reversal something coherent to work with.
Does the output keep my original format?
No — it is written as MP3 at variable bitrate quality level 2 regardless of the input. A FLAC input loses its lossless status, which is unfortunate if you reversed specifically to inspect the waveform. Use a WAV input and accept the MP3 output, or handle the reversal in a DAW if the format matters.
Is the large download worth it just for this?
The ~30 MB WebAssembly FFmpeg core from unpkg.com downloads once per browser and is then reused by every other converter on this site. If you only ever reverse one clip, it is a heavier price than a dedicated reverse button elsewhere would charge — but your file is never uploaded.