# Key and BPM finder for any song

Find a song's key, its Camelot code, and its BPM. Always free.

## How it works

1. Add a song, a beat, or a music video.
2. Audo listens to the whole file for you.
3. Read the key, the Camelot code, and the BPM, then change them if you like.

## Keys, tempo, and mixing in key

Audo's song key finder and BPM finder reads songs (WAV, MP3, M4A, AAC, FLAC, OGG, Opus, WebM, AIFF) and videos (MP4, MOV, MKV, WebM, AVI) up to 10 GB without an account, with whole files always free, 20 a day, and no sign-up. It names the key in musical terms, such as F minor, gives its Camelot code, and counts the tempo in beats per minute, with how sure it is of each.

A key is the set of notes a song is built from, and its home note is the one the melody comes to rest on. Two songs in the same or neighbouring keys can play over each other without clashing, which is why DJs sort their music by key as well as tempo. The Camelot wheel lays the 24 keys out like a clock, so neighbours are one step apart.

Tempo matters the same way: two tracks blend when their beats line up. Producers check a sample's BPM before dropping it into a session, and singers check a song's key before asking a band to play it lower. When a track needs to move, Change pitch shifts the key and Change speed changes the BPM.

Tool: Find key & BPM (`find_key_bpm`). Price: free, for whole files.

## Free API

```bash
curl -F file=@track.wav https://audo.ai/api/try/key-bpm -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.

Always free for the whole file, 20 files a day per person. 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:

No options.

## 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 `find_key_bpm`:

> Finds a song's tempo in BPM and its musical key, such as A minor, with the Camelot code DJs use and how sure it is of each. Works on audio or video. Use it to match songs for a mix, or before change_speed_pitch to reach a target tempo or key. Free. Answers directly for files up to an hour; longer files return a job_id for get_job.

Example: "Use Audo to find the key and BPM of track.wav."

## Questions

**Is it free?** Yes. Audo is always free for whole files, up to 20 a day, with no sign-up.

**What is the Camelot code?** A number from 1 to 12 and a letter for each key, from the Camelot wheel DJs use: A for minor keys and B for major ones. Songs mix smoothly when their codes match, sit one number apart, or share a number, such as 8A (A minor) and 8B (C major).

**Why does it say “or C major”?** Every major key shares its notes with a minor key: C major and A minor use the same seven. When a song could be either, the result shows the likelier one first and the other under it, with the same Camelot number.

**The BPM looks half or double what I hear. Why?** Tempo is counted on the beat you feel, and many songs can be felt at 70 or at 140 just as well. If the number seems off, halve it or double it: the beats line up the same either way.

**Can I change the key or the tempo afterwards?** Yes. Under the result, Change key opens Change pitch with your file and shows the new key as you move it, and Change tempo opens Change speed with the new BPM. The file comes along, so there's nothing to add again.

**Does it work on songs with singing, or on a video?** Yes. It listens to the whole mix, voice and all, and takes the sound from videos in MP4, MOV, MKV, WebM, AVI. Very short clips, speech, and drums on their own give it less to go on, so it says when it can't tell.

## More

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