# Reverse audio: play any sound backwards

Flip a song, a voice, or a sound effect to play from end to start.

## How it works

1. Add a recording, a song, or a video.
2. Press Reverse to turn it around.
3. Play audio backwards right here, then download it.

## What reversing does to a sound

Audo's audio reverser plays recordings (WAV, MP3, M4A, AAC, FLAC, OGG, Opus, WebM, AIFF) and the sound of videos (MP4, MOV, MKV, WebM, AVI) backwards, up to 10 GB without an account, and the first 10 minutes of each file is free, 10 times a day, with no sign-up. The whole file turns around, so the last moment comes first, at the same speed and pitch.

Sounds have a shape in time: a piano note hits hard and fades, a cymbal crashes and rings on. Reversed, each one swells up out of nothing and stops dead, which is why a reversed song sounds dreamy and strange even with the same notes. Speech turns into a language nobody speaks, its vowels intact and its consonants inside out.

Sound designers reverse sounds for risers, whooshes, and ghostly effects, and producers reverse a cymbal to lead into a drop. To change how fast it plays as well, run the result through Change speed.

Tool: Reverse audio (`reverse_audio`). Price: 1 credit a minute — $0.01/min ($0.60/hr), with no subscription — of input for whole files, charged only when a job succeeds.

## Free API

```bash
curl -F file=@cymbal.wav https://audo.ai/api/try/reverse -D response.headers -o response.body
```

Read response.headers and response.body before naming media. Handle 202, 200 JSON and errors with the complete response client at https://audo.ai/docs/api?utm_source=markdown&utm_medium=agent#responses.

Free for the first 10 minutes of each file, 10 times a day per person, with no key or account. Uploads up to 10 GB, 2 at once from one address. The response is the result itself; a job that runs longer than about 30 seconds returns 202 with a link to check on it. With an API key (`-H "Authorization: Bearer $AUDO_API_KEY"`), omitting free runs the whole file with credits if the balance covers it, otherwise the free portion if quota remains. Set free=true to prohibit spending; for paid whole files use free=false with an approved positive max_credits. A free result cut short comes with finishUrl (and the Audo-Finish-Url header when the response is the file itself): give it to the person, who pays there (from $5, no sign-up), and the whole file runs; keep checking the status link, whose finishedBy names the whole-file job and its own status link. Details: https://audo.ai/docs/api.md

## Options

Form fields with the same names as the MCP tool's inputs:

- `output_format`: The result's format: same (as the input; a video gives M4A audio), wav, mp3, m4a, or flac. Default same.

## Languages

Any language: it works on the sound, not the words.

## From an assistant (MCP)

Add https://audo.ai/mcp and sign in (setup for each assistant: https://audo.ai/setup.md). The tool is `reverse_audio`:

> Plays a recording backwards, from its end to its start. Use it for reversed sound effects, reverse reverb, or hidden messages. A video gives its reversed sound as audio. It costs 1 credit a minute, charged only if the job succeeds. Returns the result with download links, or job_id for get_job if it takes longer.

Example: "Use Audo to reverse cymbal.wav."

## Questions

**Is it free?** Yes. Audo is free for the first 10 minutes of each file, 10 times a day, with no sign-up. Whole files are $0.01 a minute ($0.60 an hour), with no subscription — see pricing.

**Can I reverse a video?** You get its sound reversed, as an audio file; the picture isn't turned around. With Save as on Same as the original, a video's reversed sound comes back as M4A, or pick MP3 or WAV under More options.

**How do I make a reverse reverb effect?** Reverse the sound, add reverb to it in your editor, then reverse it again here. The echo now swells up into the note instead of trailing after it: the rising whoosh heard before the vocals in many songs.

**How do I find a hidden message in a song?** Cut out the part you're curious about with Cut audio, so it's short, then reverse it and listen. Records have hidden reversed sounds since the 1960s, though most hidden messages turn out to be our ears finding words in noise.

**Does reversing lower the quality?** No. Every moment of sound is kept and only the order changes, so a WAV or FLAC result is the original exactly, backwards. An MP3 is compressed again when it's saved, as any MP3 is.

**Can I reverse just part of a file?** Cut the part out in the Audio editor first, then reverse it. To put it back in its place, Merge audio joins the pieces in order.

**How does the reverse singing challenge work?** Reverse a line of a song, learn to sing what you hear, record yourself, then reverse your recording to see how close it comes to the original. The Voice recorder records the take in your browser.

## More

- Every tool: https://audo.ai/llms.txt
- OpenAPI: https://audo.ai/api/openapi.json
- This page for people: https://audo.ai/reverse-audio?utm_source=markdown&utm_medium=agent