Files stay on your device
Video and audio are processed in the browser runtime, not uploaded to this server or written into a server download folder.
1
Choose the video
Add the downloaded video file
2
Choose the audio
Add the matching audio track
3
Merge in this browser
Export a new MP4 file
Local processing
Merge Audio and Video
Use ffmpeg.wasm in this browser to combine a local video file and a matching audio track into a new MP4. Files are not uploaded to the server.
[info] use ffmpeg.wasm v0.12.x
This tool runs locally in your browser. Video and audio files stay in browser memory while processing. Large files depend on device performance, memory, and browser stability, so keep this tab open until the merge finishes.
PlatformsChoose another downloader
How it works
Why merge locally?
Downloader pages stay lightweight and open direct media links. When a platform gives you a silent video, a separate video track, or a separate audio track, this page combines matching local files in your browser and exports a new MP4.
FFmpeg in the browser
ffmpeg.wasm runs through WebAssembly, so merging does not require server-side video storage or a desktop app install.
Export a local MP4
The browser creates a new MP4 and lets you save it like a normal download once processing finishes.
Best for small and medium files
Large files depend on your CPU, memory, and browser. Keep the tab open and avoid switching away during processing.
Merge guide
Audio and video merge notes
Use this tool when you already have one local video file and one matching audio file. The merge runs in the browser, which makes it useful for public-media workflows where high-quality video and audio arrive as separate tracks.
When should I use it?
Use this tool when you already have one local video file and one matching audio file. The merge runs in the browser, which makes it useful for public-media workflows where high-quality video and audio arrive as separate tracks.
- When should I use it?
- How to prepare files
- What to expect
How to prepare files
Use this tool when you already have one local video file and one matching audio file. The merge runs in the browser, which makes it useful for public-media workflows where high-quality video and audio arrive as separate tracks.
- When should I use it?
- How to prepare files
- What to expect
What to expect
Downloader pages stay lightweight and open direct media links. When a platform gives you a silent video, a separate video track, or a separate audio track, this page combines matching local files in your browser and exports a new MP4.
- When should I use it?
- How to prepare files
- What to expect
Questions
Merge FAQ
Will my files be uploaded?
No. The files are processed in the browser runtime and exported locally. The server does not receive, store, or host your original video or audio files.
Why is the first load slow?
ffmpeg.wasm needs to load its WebAssembly core before it can process media. The first visit can take longer than a normal download button.
Can I use this on a phone?
Small files may work, but desktop browsers are better for large media because merging uses CPU, memory, and browser tab resources.