Not every video plays everywhere. MOV files from an iPhone, MKV downloads, or WebM exports can be rejected by editors, social platforms and messaging apps that expect a standard MP4. Converting them usually means bulky software or an upload-based site.
This free video converter turns MOV, WebM, MKV and other formats into a widely-compatible MP4 right in your browser. There is no upload, no watermark and no sign-up — your footage stays on your device.
How to use it
- 1
Add your video
Drop in a MOV, WebM, MKV or other video file, or click to select one (up to around 300MB).
- 2
It converts to MP4
The built-in ffmpeg engine re-encodes your video to H.264/AAC MP4, the format that plays and uploads almost everywhere.
- 3
Download the MP4
Preview the converted video and download it, ready for any platform or editor.
Why use this tool
Universal MP4 output
H.264 video with AAC audio in an MP4 container is the most compatible format across phones, browsers, editors and social apps.
No upload required
Conversion happens locally, so there is no slow upload and your video never reaches a third-party server.
No watermark
Unlike many free converters, the output is clean with nothing stamped on it.
Why MP4 is the safe choice
MP4 with H.264 video and AAC audio is the closest thing to a universal video format. It plays natively in every browser, uploads cleanly to YouTube, TikTok, Instagram and Facebook, imports into every editor, and works on both iPhone and Android. Formats like MKV and WebM are excellent technically but are not accepted everywhere, and MOV — while common on Apple devices — sometimes causes issues on Windows and web uploads. Converting to MP4 sidesteps all of that.
Browser conversion vs desktop apps
For everyday clips, converting in the browser is the fastest path: no install, no upload, and complete privacy. It uses a WebAssembly build of ffmpeg — the same engine behind most professional tools — running on your own machine. Because it re-encodes, very long or 4K files can be slow or memory-heavy in a browser; for those, a desktop tool may be better, but for typical social videos this is quick and convenient.
Private by design — nothing is uploaded
Unlike most online converters that send your files to a remote server, this tool does all of its work directly inside your web browser. Your image, video or audio never leaves your device, there is nothing to delete afterwards, and there is no account to create. That makes it faster (no upload or download round-trip on top of the processing) and far safer for anything personal or client-confidential. When you close the tab, everything is gone.
Tips & best practices
- Convert iPhone MOV files to MP4 before uploading anywhere that rejects them or plays them incorrectly on Windows.
- MP4 (H.264 + AAC) is the safest choice for YouTube, TikTok, Instagram and Facebook uploads.
- If an editor refuses to import your clip, converting a MKV or WebM to MP4 almost always resolves it.
- Keep clips under about 300MB for smooth in-browser conversion; split longer videos first if needed.
- Because there is no watermark, converted files are ready to publish exactly as they are.
- For 4K or very long footage, a desktop app may convert faster, but standard social clips process quickly here.
Frequently asked questions
What formats can I convert to MP4?+
MOV, WebM, MKV and most common video formats your browser can read will convert to MP4.
Is there a watermark?+
No. The converted MP4 is clean, with no watermark and no branding added.
How big a file can I convert?+
Keep videos under roughly 300MB for smooth in-browser processing. Larger or 4K files may be slow depending on your device.
Does converting reduce quality?+
Converting re-encodes the video, which is essentially lossless at the high-quality setting used here; any difference is not visible in normal viewing.
Is my video uploaded anywhere?+
No. Everything runs in your browser, so your footage never leaves your device.
About our free creator tools
This is one of a growing set of free tools from Faceless Post, built for creators who publish consistently across YouTube, TikTok, Instagram, Facebook, X and LinkedIn. Every tool is free to use, needs no account, and adds no watermark. Most run entirely inside your browser, so your images, video and audio are processed on your own device and never uploaded to a server — there is nothing stored on our side and nothing to delete. That makes them fast, safe for client and personal files, and usable even on flaky connections once the page has loaded.
We build these because the day-to-day of content creation is full of small friction — converting a file, trimming a clip, resizing an image, cleaning metadata, grabbing a thumbnail. Handling those in one place, for free, saves you from juggling sketchy upload sites. And when you are ready to stop doing it all by hand, Faceless Post can schedule, caption and auto-publish your content to every platform from a single calendar. Explore the full free tools library or start free to automate your whole posting workflow.