Merge Audio & Video

Select a video file and a separate audio track—music, voiceover, or podcast audio. ALTools reads both directly from your device; nothing is uploaded to a server and no account is required.

Choose whether to replace the original soundtrack or mix the new audio with it. If lip-sync or beats look off, use the audio offset slider to nudge timing by seconds, then merge into one MP4 inside your browser.

Common uses include adding background music to clips, swapping noisy camera audio for a cleaner recording, dubbing over footage, or laying narration on top of screen captures.

Because merging runs locally, your raw footage stays private and you skip cloud queues. Default settings are usually quick; maximum compatibility mode re-encodes the full video and takes longer on large or HD files.

You download a single MP4 you can play on phones, post to social platforms, or import into an editor. Enable compatibility mode if a specific player has trouble opening the result.