Free online converter
MP4 to WebM Converter
MP4, MOV, WebM, GIF, JPG, PNG, WebP, HEIC, ZIP
Up to 100 MB free · 1 GB with Pro
HEIC, animated WebP input, PNG sequences and frame sequence export require Pro.
WebM is the web's native video format: open, royalty-free, and built to stream inline in every modern browser. Converting an MP4 to WebM hands you a file that's typically far smaller at the same visible quality — which means quicker page loads and lighter bandwidth for autoplay backgrounds, hero clips, and embedded demos.
Unlike a silent looping image, WebM carries full motion and sound, so it's the right pick when you need actual video — a product walkthrough, a tutorial, a looping hero — not a short muted loop. Keep the audio or drop it, trim to the moment that matters, crop off the bars, and resize to the exact width your layout calls for.
Drop in your MP4 and LightBox does the rest server-side with FFmpeg. Nothing to install, no account to open, and no watermark — your WebM downloads in seconds, and the files are cleared from the server automatically a little while after.
Why convert with LightBox
Built for fast-loading pages
WebM's modern codec compresses a bulky MP4 down hard while keeping the picture clean, so background videos and hero sections start playing sooner and eat far less bandwidth. Nudge the quality slider to trade a little detail for an even leaner file.
Your audio comes along
WebM keeps a real audio track, so voiceover, music, or dialogue survives the conversion intact. Want a muted autoplay background instead? Flip audio off and shed even more weight — the choice is one toggle, not a separate tool.
Open format, native playback
WebM plays directly in the HTML5 video tag across current Chrome, Firefox, Edge, and Safari — no plugin, no proprietary licensing, no watermark. It drops straight into a site or app the way the web expects video to work.
Free forever. Pro when you need more.
Convert common formats free. Lifetime Pro adds more capacity and permanent hosting, with no subscription.
| Limit | Free | Lifetime Pro |
|---|---|---|
| File size | 100 MB | 1 GB |
| Per day | 4 files | Unlimited |
| Files kept | 1 hour | Forever |
| Batch | 1 file | 20 files |
| Queue | Standard | Priority |
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