100% private — processing happens on your device, nothing is uploaded.
Works best with short clips (Reels, TikTok, Stories). Very large files may be slow on mobile.
By using this tool, you agree to our Terms of Use
Drop several songs or voiceovers and place each one on the timeline.
Audio can start at 0 or later—drag the clip to the right moment.
Everything runs locally with FFmpeg.wasm. Nothing is uploaded.
Creators need music beds and voiceovers without shipping files to a cloud editor.
Put one or more videos on the video track, then layer audio clips underneath and drag them into place.
Export a single MP4 with the mixed soundtrack—still 100% on your device.
Only process files you own or may edit. Music rights still apply.
Drop one or more clips on the video track. Reorder by long-press drag.
Add MP3/WAV/M4A files on the audio track. Drag left/right to set the start time.
Click Mix audio, wait for progress, then download the MP4.
Keep total media under ~200 MB. Short clips mix faster on phones. If the video already has sound, new tracks are mixed with it.
Private browser mixing only—Unvidio does not store your files.
This tool layers one or more audio files onto your video timeline with free start offsets.
The top track holds your videos (join several like a simple merge).
The bottom track holds audio clips you can slide so they don’t all start at 0.
Drop a bed music clip early, then place a voiceover later on the same audio track.
Export mixes everything into one AAC soundtrack.
FAQ
Quick answers to the most common questions about this tool.
Yes—add as many short clips as your device can handle.
Yes. Drag the audio clip on the timeline to set its start.
Yes. Videos sit on the video track and play one after another.
Video: MP4/MOV/WebM… Audio: MP3, WAV, M4A, AAC, OGG.
Yes—local processing only.
Yes, original audio is mixed with the tracks you add.
~200 MB total recommended.
Mute, merge, and add photo are on the Tools page.