Free tool
Add music to video for free, in your browser
Add music to video without uploading either file.
Your video and your music
Drag a file here, paste it, or choose one.
.mp4, .mov, .webm, .mkv. Up to 500 MB.
The video. Up to 10 minutes long.
Your video and your music never leave your browser.
Music
Drag a file here, paste it, or choose one.
.mp3, .wav, .m4a. Up to 100 MB.
An MP3, WAV or M4A track.
Mixed in this tab, not uploaded.
100% is the track as it was recorded.
More optionsloop, 3 s fade
Skips a slow intro. The song still starts with the video.
Result
Worked example
Measured on our own 26 second narrated explainer and a 33 second music bed, ducked under the narration at 60% volume.
Video in
4.2 MB, 0:26
With music
4.4 MB, 0:26
It took 3 seconds, because the picture was copied, not encoded. Under the narration the music sat 11 dB lower on average than it would in a flat mix, loud enough to hear and quiet enough not to fight the voice.
1. Drop in the video. 2. Add the music. 3. Set the mix. 4. Download the MP4.
What Interlace does
Voice and music, mixed for you.
- Interlace writes the narration and adds the voice
- Background music ducks under the narration
- Paid plans export with no Interlace watermark
Real Interlace output, unedited. Shown silent and sped up.
Your file
upbeat-loop.mp3
Ducked under speech, faded out
Questions
Asked and answered
No. Both files are read by the page and mixed by ffmpeg compiled to WebAssembly in this tab. The finished MP4 is saved to your machine and nothing goes to a server.
The music is turned down automatically whenever the video's own sound gets loud, such as a voice, and comes back up in the pauses. It is ffmpeg's sidechain compressor, keyed on the original sound. On our own narrated explainer it held the music 11 dB lower on average than a flat mix. Pick the flat mix instead when the original sound is ambience you want to sit level with the music.
The picture is copied into the new file untouched, so ffmpeg only has to build the sound track. When a video's picture cannot be copied into an MP4, for example an old WebM, the page falls back to a full H.264 encode, which runs at roughly real time.
A longer song is cut at the end of the video, with a fade if you leave fade out on. A shorter song loops back to its start until the video ends, or, with looping turned off, stops and leaves the rest of the video with its own sound only.
The tool will mix any file you give it, but YouTube, Instagram, TikTok and LinkedIn match copyrighted music and may mute or block the video. Use a track you have a licence for, or one from a royalty free library.
500 MB and 10 minutes. Everything runs inside one browser tab, and a tab has a fixed memory budget. Past those limits a desktop editor is the better tool.
Turn this into a video
Create an account and start from a document, script, or prompt.