Audio Pitch Changer

What it does

Upload an audio file (MP3, WAV, M4A, OGG, FLAC, or anything else your browser can decode) and shift its pitch by up to ±12 semitones. Useful for transposing a song into a key your voice can sing, getting a karaoke backing track to match your range, prepping vocal samples for a producer who wants everything in C, or just hearing what your favorite track sounds like a fifth higher.

Pitch shift here is the simple kind: it changes the playback rate, which moves both pitch and tempo together (one semitone up = ~5.9% faster, one semitone down = ~5.6% slower). That's the same algorithm you get when you slow a record down on a turntable — clean and artifact-free, but length changes too. If you need pitch-only or tempo-only (independent), you'd want a phase-vocoder tool; those are much heavier and not always free.

The whole pipeline runs locally via the Web Audio API. Your file is decoded into a buffer, replayed at the new sample rate, and re-encoded as a 16-bit WAV. No upload, no server, no waiting in queue. Works on files up to roughly 10 minutes / 100 MB before your browser starts complaining about memory.

How to use it

1. Upload your audio file (drag-drop or click to browse).
2. Use the +/− buttons or the slider to set the pitch shift in semitones (−12 to +12).
3. Click Preview to hear the result before exporting — useful for finding the right key by ear.
4. When you're happy, click Download to save a 16-bit WAV. Filename includes the semitone offset (e.g. song-up3.wav).
5. If you need an MP3 for sharing, run the WAV through any MP3 encoder afterward (or use our audio-converter tool).

How it works

Pitch shift = playback-rate change. We decode the input into a Web Audio AudioBuffer (whatever sample rate the source uses), then write each sample to a new buffer at a stretched/compressed rate. The math is simple: newRate = originalRate × 2^(semitones/12). Twelve semitones = factor 2 = one octave up.

The new buffer is fed to an OfflineAudioContext(which renders faster than realtime), then encoded with a minimal in-browser WAV writer (RIFF header + PCM int16 samples). No third-party libraries, ~50 lines of code.

When to use this tool

• Transposing karaoke or backing tracks to fit your vocal range.
• Slowing down a guitar lick or solo to learn it by ear (negative semitones = slower + lower pitch).
• Prepping vocal/instrument samples to a target key for a producer.
• Quick pitch experiments on phone recordings when you don't want to install Audacity.

When not to use it

• Pitch-only shifts (when you need to keep the original tempo) — this tool changes both. For vocal-style preserved-tempo shifts, use a phase-vocoder DAW plugin.
• Production-quality vocal tuning — this is a coarse semitone tool, not a Melodyne/Auto-Tune replacement.
• Files larger than ~100 MB — the browser will run out of memory on most laptops.
• Anything where lossless quality matters end-to-end — output is 16-bit/44.1 kHz WAV, fine for most uses but not 24-bit or higher.