MP4 to MKV

No. Conversion runs inside your browser through the WebCodecs API, using your device's own video encoder. The file is read from disk into a Web Worker and never sent anywhere, which is why there is no queue and no daily limit.

Because your device is doing the encoding rather than a server farm. Speed depends on your hardware and the video length. The trade is deliberate: server converters are faster but require handing over your file, and most cap size or add a watermark.

The limit is your device's memory, not a business rule. The finished file is assembled in memory before download, so very large inputs risk exhausting the tab. We reject those up front instead of crashing halfway through a long encode.

Whichever the target container supports that your browser can actually encode, picked at runtime and shown on each finished file. That is why the same conversion can produce a different codec on a different device.