Add audio to a video, free, with no watermark

Pick one audio file, then drop your videos onto this page. A few seconds later each finished video lands in your downloads folder with that audio under it. It's free, there's no account and there's no watermark.

It's matched to the video's own length either way. Shorter audio loops from the start to fill the video; longer audio is cut off at the video's length. The output is never longer or shorter than the video you dropped in.

By default it's replaced by the new audio. Tick "keep each video's own sound too" and the original plays underneath the new track instead, both turned down slightly so neither clips.

No. The picture is never decoded or re-encoded. Its frames are copied straight into a new file, so the resolution, the aspect ratio, the frame rate and the quality all come out exactly as they went in. Only the sound is built fresh.

That's the point of it. Pick your audio once, then drop as many videos as you like. Each one gets the same track, matched to its own length, and downloads on its own.

No. The whole thing happens inside your browser tab. Neither your videos nor your audio touch a server, so there's nothing sitting in somebody's bucket. You can turn your wifi off and it still works.

Because the finished file is held in memory in the tab, and a long clip on a small laptop is how a tab runs out of it. Anything over 60 seconds is refused rather than quietly cut short.

Video: MP4, MOV, WebM and MKV. Audio: MP3, WAV, M4A, OGG and FLAC. You get the same video container back that you put in.

No. There's no email box, no login and no trial that expires. Open the page, pick a file, and go.

It's free and there's no catch on this page. It's one small piece of Quick Throttle, a paid app that writes the lines, generates the footage and renders hundreds of videos at once. This page is a part you can have for nothing.