I understand you're looking for a guide on applying an — but just to be clear, you cannot apply an XDelta patch purely "online" (i.e., inside a web browser without downloading files).
: Frequently recommended by the ROM hacking community for its ease of use and reliability. How to Apply an Xdelta Patch Online Follow these steps to successfully apply your patch: How to create and use Xdelta patches - Ninten's Corner apply xdelta patch online new