I had a recurring frustration: I needed to mute a video before sharing it. Every tool I found either uploaded the file to a server, added a watermark, or required me to create an account.

I know a single FFmpeg command handles this in milliseconds. But most people are not going to open a terminal for something like this.

So I built Remove Audio — a free, browser-based tool that strips the audio from any video, locally on the user's device.

The core idea

The whole thing runs on FFmpeg.wasm, a WebAssembly port of FFmpeg. When a user drops a video in, the browser downloads the WASM binary once and then runs FFmpeg entirely locally. Nothing leaves the device.

The underlying operation is essentially:

ffmpeg -i input.mp4 -an -c:v copy output.mp4

-an drops the audio track. -c:v copy tells FFmpeg to copy the video stream without re-encoding, which means zero quality loss and fast processing even on large files.

Why not just use a server?

Server-side processing is simpler to build. But it has real downsides for the user:

• Their file travels over the network (slow for large videos)
• It lives on someone else's machine during processing
• You need infrastructure, storage, and bandwidth costs

WebAssembly flips this. The compute happens on the user's machine. The only thing the server needs to serve is the WASM binary, which is cached after the first load.

What made it tricky

Cross-origin isolation. FFmpeg.wasm requires SharedArrayBuffer, which requires the page to be cross-origin isolated. That means setting Cross-Origin-Opener-Policy: same-origin and Cross-Origin-Embedder-Policy: require-corp response headers. This broke some third-party embeds and required careful workarounds.

Mobile Safari. iOS has stricter constraints on WASM memory and threading. I had to test and tune specifically for iPhone, where a lot of people do casual video editing.

Format handling. Remuxing MKV or MOV files while copying streams is not always straightforward. Some container formats need extra handling even when you are just copying the video stream directly.

What I shipped

remove-audio.com is free, no account required, works on Mac, Windows, iPhone, Android, and any modern browser. Supports MP4, MOV, MKV, AVI, and WEBM. Available in English, Spanish, French, German, and Dutch.

If you are building something where users need silent video — content tools, training platforms, social media schedulers — this is something you can just point people to.

Happy to answer questions about the FFmpeg.wasm integration or the COOP/COEP setup if anyone is curious.