Is my file uploaded anywhere?

No. Every conversion happens entirely inside your browser using your own hardware. Your files never leave your device and are never sent to any server.

Why can I only add one type of file at a time?

Images, video, and audio each use a different conversion engine. The queue locks to the type of the first file you add. Hit "Clear All" to start a new batch with a different file type.

Is there a file size limit?

No, however very large files are limited by the memory available to your browser tab. Most files under a few gigabytes work fine.