About WebM
WebM is what video looks like when it is designed by and for the web. Introduced by Google in 2010 and built on fully open, royalty-free codecs (VP8, VP9, and now AV1), it plays natively in every modern browser and compresses noticeably better than typical MP4 video at the same visual quality. Screen recorders, browser capture tools, and chat platforms like Discord produce it constantly.
Its weakness is everything that isn’t a browser. iPhones won’t play WebM, most TVs and consoles ignore it, and professional editing software supports it grudgingly at best. That mismatch defines both conversions this site offers: WebM to MP4 when a clip needs to leave the web (a real re-encode, done honestly), and MP4 to WebM when video is headed for a website and smaller files are the goal.
Both directions run entirely in your browser — recordings never upload, there are no size tiers, and encoding WebM is among the most reliably-supported conversions here because the codecs are the browser’s own.
Strengths
- Fully open and royalty-free — no patent licensing anywhere in the stack
- Excellent compression: smaller files than typical MP4 at comparable quality
- Native playback in every modern browser, ideal for websites and web apps
- The natural output of screen recorders and browser-based capture tools
- Encoding support is universal across current browsers
Limitations
- iPhones, most TVs, and consoles refuse to play it
- Editing software support ranges from grudging to absent
- Always re-encodes when converting from MP4-world video — no lossless shortcut
- A poor choice for sending to people whose devices you don’t control