How does the browser-based video converter work?

It uses FFmpeg compiled to WebAssembly (WASM) running entirely in your browser. Your video file is never uploaded — conversion happens locally on your device using your CPU.

Which video formats are supported?

MP4, MOV, AVI, MKV, and WEBM. You can convert between any combination — for example MKV to MP4, MOV to WEBM, or AVI to MKV.

Why does the first conversion take longer?

The first run downloads the FFmpeg WASM core (~33 MB) from a CDN and caches it in your browser. All subsequent conversions start immediately.

Is there a file size limit for video conversion?

No hard limit. The practical ceiling is your device's available RAM. A 1 GB video file typically needs 2–3 GB of free RAM for processing. For very large files, a desktop with 8+ GB RAM is recommended.

How long does video conversion take?

Conversion time depends on file size, target format, and your device's CPU speed. A 100 MB MP4 typically converts in 30–90 seconds. FFmpeg processes video using your browser's available CPU threads.

Free WEBM to MP4 Converter — browser-based, no upload

Convert WEBM to MP4 for free.

Upload a WEBM recording and convert it to a widely compatible MP4. Runs entirely in your browser via FFmpeg WASM — nothing is uploaded.

FFmpeg loads once (~33 MB) then caches in your browser. First conversion may take 10–20 seconds to initialise. Large video files may take several minutes depending on your CPU speed.

Convert Video

1. Upload video file

Drop files here

or click to browse

VIDEO/* · .MP4 · .MOV · .AVI · .MKV · .WEBM · .FLV · .WMV · .M4V · Max 50 MB

2. Choose output format

Files never uploaded

FFmpeg WASM — browser-native

No signup required