Add Audio to Video Online - Free & Private

Merge audio into any video directly in your browser. Replace the original soundtrack or mix in background music, trim and chain multiple audio clips, and download instantly. No upload to servers, no watermark, no signup.

Video Audio Merger Features

Multiple Audio Clips

Add several audio files, drag to reorder, and trim each clip's start and end. Clips play back-to-back over your video.

Replace or Mix

Replace the original soundtrack entirely, or mix new audio with the existing sound and balance both volumes.

No Re-encoding

The video stream is copied as-is, so merging finishes in seconds with zero quality loss.

Private & Free

Everything runs locally in your browser. Files never leave your device. Free, no watermark, no account.

How to Add Audio to a Video

Upload your video

Select an MP4, WebM or MOV video file. A preview player appears instantly.

Add audio clips

Add one or more audio files (MP3, WAV, M4A, OGG). Reorder and trim them as needed.

Choose the audio mode

Replace the original sound, or mix the new audio with it and adjust volumes.

Merge and download

Click merge. Processing happens in your browser and the video downloads when done.

When to Add Audio to Video

Background Music for Any Video

Add music to video files in seconds: drop in a soundtrack, position it on the timeline, and give flat footage instant mood and rhythm.

Vlogs and Short-Form Videos

Give vlogs and short clips a professional feel. Mix background music under your voice and balance both volumes so the narration stays clear.

Voiceover for Silent Screen Recordings

Recorded a demo without a microphone? Add sound to video afterwards by merging a separately recorded narration track over your screen capture.

TikTok, Reels and Shorts Audio

Prepare clips with your chosen track before uploading, so the exact audio timing you designed survives on TikTok, Instagram Reels, and YouTube Shorts.

Course and Tutorial Narration

Merge recorded explanations into lecture slides or tutorial videos. Chain multiple audio clips to match each chapter of the lesson.

Gaming Highlight Music

Turn raw gameplay captures into montage-ready highlights by adding hype music, or mix it with the original game sound for atmosphere.

Copyright-Safe Music Swaps

Replace a copyrighted soundtrack with royalty-free music before publishing. The replace mode strips the original audio completely.

Birthday and Wedding Videos

Add a meaningful song to celebration footage. Trim the track so the chorus lands on the key moment, then preview before downloading.

Tips for Adding Audio to Video

Preview before you merge

Use the built-in real-time preview to hear exactly how the added audio sits over the video before creating the final file.

Trim clips to hit the beat

Drag the handles on each audio block to cut silence or align a musical drop with the on-screen action.

Duck the original sound

In mix mode, lower the original volume slider and raise the added audio so the music stands out without drowning dialogue.

Mind the video length

The output always matches the video duration. Audio extending past the end is cut off, so position clips within the video timeline.

Extract audio from another video

The audio slot also accepts video files — drop in another clip to reuse its soundtrack without a separate extraction tool.

Compress large videos first

Files up to 500 MB work on desktop (200 MB on mobile), but merging is faster and smoother if you compress oversized videos first.

Why Choose Our Video Audio Merger

Free with no watermark

Add audio to video for free and download clean MP4 or WebM files without watermarks or hidden limits.

Private in-browser processing

The whole merge runs locally via WebAssembly. Your video and music never leave your device or touch a server.

No video re-encoding

The video stream is copied bit-for-bit, so quality is identical to the original and merging finishes in seconds.

Timeline editing with live preview

Drag audio blocks along the timeline, trim with handles, and hear the result instantly before you commit.

Replace or mix modes

Choose to swap the original soundtrack entirely or blend new audio with it using independent volume sliders.

No signup required

Open the page and start merging — no account, no email, no installs.

Frequently Asked Questions

No. The merge runs entirely in your browser via WebAssembly. Your video and audio never leave your device.

No. The video stream is copied without re-encoding, so quality is identical to the original.

The output always matches the video length. Extra audio is cut off; if the audio is shorter, the remainder of the video is silent.

Video: MP4, MOV (output MP4) and WebM (output WebM). Audio: MP3, WAV, M4A, AAC, OGG, or the audio track of another video file.

The processing engine (about 30 MB) downloads on first use and is then cached by your browser, so later merges start instantly.

Yes. Add as many clips as you need, drag each block along the timeline to position it, and use the handles on both ends to trim. Clips play at exactly the spots you place them.

Choose mix mode, then use the two volume sliders — one for the original soundtrack and one for the added audio. Preview playback in real time until the balance sounds right, for example lowering the original to keep narration clear.

Yes, it runs in mobile browsers like Safari and Chrome. Files up to 200 MB are supported on mobile (500 MB on desktop), so compress very large videos before merging on a phone.

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