Convert MOV to MP4

How MOV to MP4 works

The file is read with a FileReader, rewritten in memory and offered as a download. This is why large PDFs are limited by your device's RAM rather than by an upload size limit. A 200 MB scan never crosses the network, so the slowest part is your own disk.

That is the whole architecture: static files, one script, no upload endpoint to leak or log. Close the tab and the work is gone.

Why iPhone videos do not play everywhere

Apple records into QuickTime containers, and recent iPhones encode with HEVC rather than H.264. Windows 10 without the HEVC extension cannot decode it, many Android players cannot either, and a browser tab refuses outright.

The fix is to decode the HEVC and write H.264 inside an MP4. That is exactly what this page does, which is why the output plays on everything from a smart TV to a five-year-old Android phone.

The one flag that matters

MP4 keeps its index — the table that says where each frame lives — at either the start or the end of the file. Camera apps often write it at the end; a player then has to read the whole file before it can show the first frame, which is why a video seems to hang when streamed.

The +faststart flag moves the index to the front. It costs nothing and it is the difference between instant playback and a spinning circle.

What is lost

Slow-motion metadata is dropped: a 120 fps clip recorded with a slow-motion flag becomes a normal-speed video at its real frame rate. HDR is converted to standard dynamic range, which flattens the highlights slightly.

If either of those matters, keep the original MOV and convert only a copy for sharing.

Good to know

• Works offline once loaded, including on flights and in locked-down networks.
• No file size limit beyond your device's own memory.
• Free to use, with no account and no usage counter.
• Results are produced locally, so they are not logged or shared with anyone.

Questions