TL;DR: Re-encodes MP4 into VP9 WebM for smaller files and royalty-free open-web streaming; expect a slower encode for the size savings.
Convert MP4 to WebM online for free — re-encode MP4 video as WebM (VP9) for smaller files and royalty-free open-web streaming.
Unlike the freemium tools it replaces, MP4 to WebM has no 'pro' upsell, no task-per-day cap, and no stamp on your output. Server-side processing happens in a sandboxed container that forgets your file as soon as the download finishes.
Convert MP4 to WebM online for free — re-encode MP4 video as WebM (VP9) for smaller files and royalty-free open-web streaming. Use it when you need a quick, private, no-account way to handle a file in the browser, or when you want an auditable open-source alternative to cloud converters, ad-heavy utility sites, and desktop apps. The page at /tools/mp4-to-webm is designed for one clear job: upload or provide the input, choose only the options that matter, and download the result without creating an account or passing through a sales funnel.
Many non-PDF utilities run entirely in your browser; conversion or media operations that need backend libraries use the same isolated container model. Temporary input and output files are not used for analytics, model training, advertising profiles, or product telemetry. The public demo uses anonymous page-view analytics only; file bytes, extracted text, filenames, passwords, signatures, and generated results are outside that analytics path. If your organization needs stricter controls, you can self-host all 214 PrivaTools utilities and keep processing on your own infrastructure.
Before running MP4 to WebM, confirm that the source file opens correctly and that you have permission to process it. Keep the original asset, choose the smallest output that still matches your target app, and test the result before deleting source media. For sensitive material, review the downloaded result before sharing it. For large files, give the browser time to finish the download and avoid refreshing the page mid-run. If a password, damaged upload, unsupported codec, or malformed document blocks processing, PrivaTools returns a plain-language error so you can pick the next recovery step instead of guessing.
MP4 to WebM is intentionally narrow: it does one file task and hands the result back as a normal download. That makes the output easy to inspect, rename, archive, attach to email, or feed into another tool. If you need a repeatable workflow, save the page, bookmark a Pipeline recipe, or self-host the API so the same steps can run from internal scripts. The interface avoids accounts and cloud folders on purpose: the safest default for private files is to process only the current request, return the result, and leave long-term storage under your control.
MP4 to WebM runs in any modern browser on Windows, macOS, Linux, Android, and iOS — there is nothing to install, no extension to add, and no desktop app to keep updated. Because the interface is a single page, you can bookmark it, send the link to a colleague, or open it on a phone and get the same result you would on a laptop. There are no watermarks stamped onto your output, no sign-in wall before the download, and no paid tier that unlocks the “real” version later — the MP4 to WebM you see is the complete tool. For teams that would rather keep everything in-house, the same endpoint ships in the MIT-licensed, self-hostable build, so you can run it behind your own firewall with identical behaviour and no outbound calls. That combination — instant in the browser for individuals, fully self-hostable for organizations — is what keeps a private file genuinely private from upload to download.
WebM uses VP9, which is royalty-free and often produces smaller files than H.264 at the same quality. Ideal for hosting video on the open web.
Every modern desktop browser plays WebM. Safari on iOS supports it from iOS 16 onward. For maximum compatibility, MP4 is still safer.
Typically 20–40% smaller than the equivalent MP4 at the same visible quality.
Working with PDFs too? Try our Merge PDF, Compress PDF, PDF to Word, or all 214 tools.