Add Audio to Video
Upload a video and an audio file to combine them — replacing the video's existing sound or adding a track to a silent clip — then download the merged result. All processing happens in your browser.
Your video is processed on your device and is never uploaded to our servers.
Only use this tool with files you own or have the right to process.
Drag a video here or choose one
MP4, WebM, MOV, or MKV
What this tool does
Adds an audio file to a video, either replacing the original sound entirely or mixing the new audio with what is already there.
When to use it
- A clip you want background music on.
- A silent video that needs pre-recorded narration.
- A clip whose original audio is poor and should be replaced with a cleaner recording.
- You want light music underneath the existing speech rather than instead of it.
How to use it
- Put the video on the drop area or choose it.
- Add the "Audio file" in MP3, WAV, M4A, AAC or OGG.
- Choose "Replace the original audio completely" or "Mix the new audio with the original audio".
- Click "Apply", then "Download video".
A practical example
Input
A one-minute silent promo clip with a music file, in replace mode.
Output
The same clip with the music playing from the start.
Limitations
- Mix mode requires the video to already have an audio track; without one there is nothing to mix against, and the tool says so.
- The levels of the two tracks cannot be set separately in mix mode.
- If the audio is shorter than the video it ends early; if it is longer, the excess is cut.
- The audio always starts at the beginning; a start offset within the clip is not offered.
Privacy and processing
The video and the audio file are both processed inside your browser and neither is uploaded to our servers.
Technical notes
- Merging runs locally through FFmpeg.wasm; mix mode combines both into a single track in the output.