Why Do This in Your Browser?
Audio trimming is the most common audio task and the one cloud sites monetize most aggressively. The mp3 cutter category alone has dozens of sites with the same UI: upload, set in/out, download. Every single one runs the trim server-side and bills the bandwidth back to you in ads or upgrade nags.
FFmpeg.wasm trims with the `-ss` and `-to` flags, just like desktop FFmpeg. When the cut points land near keyframes, the trim is a stream-copy (instant, bit-exact). When precision matters more than speed, the tool transcodes the cut frame-accurately. Either way, the source never leaves your device.
How It Works
Drop an audio file. The tool decodes the waveform via Web Audio API and renders an interactive waveform display. Drag the start and end handles; click on the waveform to scrub; press space to play/pause from the current cursor position. Keyboard shortcuts: I for in-point, O for out-point, space for play/pause, arrow keys for frame-step.
Export modes: 'Fast trim (stream-copy)' uses FFmpeg's `-c copy` for instant bit-exact cuts, with cut points snapping to the nearest keyframe — typically within ±100ms of the chosen point. 'Precise trim' transcodes to give you exact cuts at the millisecond level, slower but frame-accurate. Default is precise.
Tip: For format conversion alongside trimming, the Audio Converter tool handles container/codec changes. To compress the trimmed output, the Audio Compressor tool exposes bitrate controls. For auto-detecting silence rather than manually setting in/out points, the Audio Silence Remover trims leading/trailing dead air and can compress mid-clip gaps. To slow a long interview for transcription before trimming, the Audio Tempo Changer drops speed without affecting pitch.
Common Use Cases
How We Compare
Honest read on free, paid, and self-hosted options for this kind of job:
See also: The Audio Waveform Generator renders a static SVG/PNG waveform image from any audio file — useful as a podcast cover or thumbnail.