Upload the video plus the music, narration, podcast intro, or other audio track you want to add. Supports MP4, WebM, MOV, and common audio formats like MP3, WAV, AAC, and OGG.
Choose Replace if the new track should fully replace the original sound, or Mix if you want background music under the existing audio.
Export a single MP4 with your new soundtrack, ready for YouTube, presentations, product demos, or social clips.
Your files never leave your device. All audio processing happens in your browser — no server uploads.
No registration, no file limits, no watermarks. Add audio to as many videos as you need, completely free.
Add background music, swap noisy camera audio, or combine narration with the original soundtrack without leaving the browser.
Add background music to a silent product demo, slideshow, or merged clip before publishing.
Replace noisy on-camera audio with a clean voiceover recorded separately.
Mix intro music under a tutorial, webinar, or screen recording without destroying the original dialogue.
Add a soundtrack to a travel montage or reel after merging your clips.
| Format | Description | Best For |
|---|---|---|
| MP4 (video input/output) | H.264 video | Universal video with added audio |
| WebM (video input) | VP8/VP9 web video | Web video content |
| MOV (video input) | Apple QuickTime video | iPhone recordings |
| MP3 (audio input) | Compressed audio | Music tracks, voiceovers |
| WAV (audio input) | Lossless audio | High-quality narration, studio audio |
Use Replace when the original mic track is unusable, and Mix when you want to keep speech while adding music underneath.
Background music should usually sit lower than dialogue. If the voice is hard to hear, reduce the music level before exporting.
Trim the audio file first if you need an exact intro, loop, or voiceover section to line up with the video.
When the final MP4 is ready, compress the video if you need a smaller file for upload, email, or messaging apps.
FyleTools uses FFmpeg compiled to WebAssembly to mux the new audio track into the video container. In replace mode, the original audio is discarded. In mix mode, both audio streams are blended with controllable levels using FFmpeg's amix filter. The video stream is copied without re-encoding.