Converting a set of files in one pass
Each file is decoded and written out as JPG in turn, keeping its original name and dimensions and changing only the extension. The results appear as they are finished, so you can start downloading before the whole batch completes.
PNG to JPG in short
JPG (also written JPEG) is the oldest widely supported photo format. It uses lossy compression, which keeps photographs small but discards some detail every time the file is saved.
Transparent areas are filled with white, because JPG has no alpha channel.
Practical limits
Processing happens one image at a time inside the browser tab, so a batch of very large photographs takes a while and uses memory. If a job stalls, split it into smaller groups. The ZIP archive is assembled without extra compression, since the images inside are already compressed.