WebP does what PNG does, usually at half the size or better. For anything going on a website that is a straightforward win.
Check destination support and transparent edges. This encoder uses a quality setting, not a lossless-WebP mode. Keep the PNG original for editing.
Transparent areas become white in JPG. PNG preserves existing transparency but does not remove a JPG's background.
PNG ignores the quality slider. JPG and WebP encoding can change detail; this tool has no lossless-WebP switch.
WebP keeps transparency, so a logo or cut-out with a clear background converts cleanly. The saving is usually good for photographs and varies for flat graphics. The tool shows the size before and after, so you can see whether it was worth it.
Some old programs and forms do not accept WebP, so keep the PNG as well when the file is going somewhere you do not control. On a website you control, use WebP and test the page.
No. Changing encoding cannot reverse earlier compression or create missing pixels.
What can be opened depends on your browser. JPG, PNG and WebP always work, and a file of another type may need to be saved as one of those in another program first.
Yes. WebP supports transparency, so a cut-out or logo keeps its clear background.