Audio Speed Changer
Speed up or slow down audio (0.5×–2×) in your browser, keeping the pitch natural. Free, private, no signup or upload.
About the Audio Speed Changer
This free audio speed changer makes any track play faster or slower — from half speed to double speed — while keeping the pitch natural so voices and music do not sound like chipmunks or slow-motion. It is great for speeding through a lecture, slowing a song to learn a part, or tightening the pace of narration.
All processing runs in your browser via FFmpeg WebAssembly, so nothing is uploaded. The engine (about 30 MB) is downloaded from a CDN the first time and cached, so the first run takes longer than later ones. By default the tool preserves pitch using time-stretching; you can turn that off to get the classic tape-style pitch change if you prefer.
A quick note: very large speed changes can introduce subtle artifacts, and slowing audio down cannot add detail that was not recorded. Moderate changes sound the most natural. Files up to 100 MB are supported.
How to Use the Audio Speed Changer
- 1Choose an audio file, up to 100 MB.
- 2Set the speed from 0.5× (slower) to 2× (faster).
- 3Keep 'Preserve pitch' on for natural voices, or turn it off for a tape-style effect.
- 4Click Change Speed, preview and download the result.
Frequently Asked Questions
Is my file uploaded to a server?
No. All processing runs in your browser using FFmpeg compiled to WebAssembly. Your file never leaves your device — only the converter engine is downloaded, once.
Why is the first run slow?
The first time you use any converter here, the browser downloads the FFmpeg core (about 30 MB) from a CDN and compiles it. It is then cached for the session, so later runs are much faster.
Does the pitch change too?
Only if you want it to. With 'Preserve pitch' on (the default) voices and music keep their natural pitch. Turn it off for the classic sped-up or slowed-down tape effect.
How fast or slow can I go?
From 0.5× (half speed) to 2× (double speed). This range keeps quality high; extreme changes tend to add artifacts, especially with pitch preservation.
Is there a file size limit?
Yes, 100 MB per file. Because everything runs in your browser's memory, very large files can be slow or run out of memory. Trim long clips first if you hit the limit.