FileTransmuteFree online file converter

Free Video Converter Tools

Convert and compress video right in your browser — MP4, MOV, AVI, MKV, WebM — powered by FFmpeg compiled to WebAssembly. Nothing is uploaded.

Convert and compress video in your browser

Convert MP4, MOV, AVI, MKV, and WebM, or shrink a large clip down for email, messaging, or an upload limit — all without sending your footage to a server. The tools run FFmpeg compiled to WebAssembly, the same engine desktop apps use, right inside the page.

Fix videos that won't play

A .mov from an iPhone or a .mkv from a download often won't open in the app you need. MOV to MP4, MKV to MP4, AVI to MP4, and WebM to MP4 repackage the video into MP4 — the format that plays virtually everywhere, from social platforms to presentation software.

Extract audio and compress

Pull the soundtrack out of a video with MP4 to MP3 for a podcast clip or a music track, or use Compress Video to cut file size when a clip is too big to share. You choose the trade-off between size and quality.

Private, no-upload video conversion

Uploading video is slow and, for personal or unreleased footage, risky. Because conversion happens on your own machine, there's no upload wait and nothing leaves your device. Note the FFmpeg engine (~30 MB) downloads once on first use and is then cached, so later conversions start quickly.

Not sure which tool you need?

Privacy, proven — live
Online
0 BUploaded to our servers
0Requests carrying your data
0Files stored by us
Processed on your devicedrop a file
Conversions run entirely in your browser. Turn off your Wi-Fi and try it — it still works. Nothing leaves this device.

Frequently asked questions

No. Video conversion and compression run in your browser with FFmpeg WebAssembly, so your footage never leaves your device.

The FFmpeg engine (~30 MB) downloads once on first use, then is cached — subsequent conversions start much faster.

Yes. All in-browser video tools are free with no sign-up and no daily limit.

Yes. MP4 to MP3 extracts the audio track and saves it as an MP3.

Small and medium clips convert smoothly. Very large files depend on your device's memory, since everything runs locally — on low-end phones, expect longer processing.

Yes, once the page and engine have loaded, in-browser conversion keeps working without a connection.

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