Swap a video's audio track for a different audio file - locally in the browser, no upload.
Running locally on your device ...
Running locally on your device ...
0%
Your files never left your device
No. Everything runs in your browser - your file never leaves your device. How this is verifiable
A timelapse that should get its own music track instead of the original wind noise, a silent clip with new narration, or a video that needs the cleaner audio from a separate microphone recording - this tool replaces a video's entire audio track with a different audio file.
Drop exactly one video and exactly one audio file at the same time - the tool automatically recognizes which file plays which role (by file type, not by drop order). Two videos or two audio files are honestly refused. If the audio file is longer or shorter than the video, it stays unchanged - no automatic trimming or looping.
Everything runs locally in the browser with mediabunny (MPL-2.0, self-hosted, no third-party CDN) on the browser's native WebCodecs API. Your files are not uploaded.
| Input formats | MP4, M4V, MOV, MKV, WEBM, MP3, WAV, M4A, AAC, OGG, OPUS, FLAC |
|---|---|
| Output format | MP4 |
| Batch processing | Yes |
| Processing | Locally in your browser (WebCodecs) |
| File upload | None |
Limitations: Needs exactly one video and exactly one audio file. No automatic length matching (trim/loop) between picture and the new audio. Full re-encode, so it takes longer than a pure stream copy. Each file ~600 MB limit individually (the browser tab's memory limit: the video and audio tracks are decoded and re-encoded into one file at the same time, so streaming does not help here the way it does for single-file tools).
No. The whole replacement happens locally in your browser.
No, the tool recognizes video and audio automatically by file type, regardless of order.
Both stay at their original length - nothing is automatically trimmed or repeated.
No. The tool needs exactly one video and exactly one audio file and honestly refuses anything else.
A small, usual re-encoding loss is unavoidable because the video is recomposed.
Merge videos · Remove video audio · MP4 to MP3 · Video watermark · Video speed · Crop video