Free Tool
Convert any video to MP4 or WebM — free, no upload
Switch between MP4 (AVC), WebM VP9, and WebM VP8 entirely in your browser.
The problem
Different platforms need different video formats. YouTube prefers MP4, web video players often need WebM, and Safari has historically required specific codecs. Cloud converters upload your file to a server and take minutes. Download tools install unwanted software. There's no fast, private option.
The NSS solution
NSS Video Format Converter re-encodes your video using your browser's built-in codecs. Choose MP4 (AVC/H.264) for universal compatibility, or WebM VP9 for the best web compression. Your video never leaves your device.
How to use it
- 1
WebM to MP4 for email and downloads
Screen recordings and browser-captured clips are often WebM. Convert to MP4 for email clients, mobile devices, and Windows Media Player compatibility.
- 2
MP4 to WebM for web video
WebM VP9 files are typically 20–40% smaller than MP4 at the same quality, which means faster page loads. Convert before embedding in websites.
- 3
Normalize format across a project
When combining footage from different sources (phone, screen recorder, camera), convert everything to the same format before editing.
Step-by-step guide
- 1
Select your output format
Choose MP4 (AVC), WebM VP9, or WebM VP8 depending on your target platform.
- 2
Upload your video
Drop or click to upload. The video plays through at real time while being re-encoded.
- 3
Download the converted file
When complete, download the converted video. File size depends on the codec and source quality.
Common questions
How long does conversion take?
The video must play in real time during conversion — one minute of video takes about one minute to convert.
Is MP4 or WebM better for websites?
WebM VP9 gives better compression (smaller files) for the same quality. MP4 is universally compatible with all browsers, devices, and email clients.
Will my video be uploaded to a server?
Never. Conversion uses browser-native codecs and runs entirely on your device.
Ready to try it?
No account. No subscription. No images uploaded to any server.
Convert video format free→