The music drowns out the original sound — what now?

Set the new audio volume to 30–50%. The mix also passes through a limiter, so layering never clips.

What if the music is longer than the video?

It is trimmed automatically — the output is always exactly as long as the original video.

Are my files uploaded to a server?

No. Everything runs locally in your browser via WebAssembly. Files never leave your computer and are discarded when you close the page.

Do I need to sign up or pay?

No. The site is completely free, requires no account, has no usage limits and adds no watermarks.

🎙️

🎙️Add or Replace Video Audio Online - Background Music & Voiceover

Swap in a new soundtrack, or keep the original audio and lay music underneath it. The picture is copied rather than re-encoded, so this runs fast and the quality is untouched. Music shorter than the video can loop automatically, and anything longer is trimmed to the video length.

Free · No sign-up · Runs in your browserLast updated: 2026-10-26

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How to use Replace Video Audio

1Upload a video, then pick an audio file
2Choose replace or mix, and set the volume of the new audio
3Click start and download the result

FAQ

The music drowns out the original sound — what now?: Set the new audio volume to 30–50%. The mix also passes through a limiter, so layering never clips.
What if the music is longer than the video?: It is trimmed automatically — the output is always exactly as long as the original video.
Are my files uploaded to a server?: No. Everything runs locally in your browser via WebAssembly. Files never leave your computer and are discarded when you close the page.
Do I need to sign up or pay?: No. The site is completely free, requires no account, has no usage limits and adds no watermarks.