photopea[.]com/
This actually looks pretty good, with support for layers, history etc., and can work much like an installed app [as a PWA] if/when using Google or Edge browsers. For me the make/break issue on this sort of thing, is that like most in the US with cable broadband, my upload speed is vastly reduced -- a 5-6 MB jpg wouldn't likely be a problem, but my .tif files [without image compression] run 20-500 MB each, and that would be impractical.
Info on PWAs [thurrott[.]com also has several articles]:
developers.google[.]com/web/progressive-web-apps/
developer.microsoft[.]com/en-us/windows/pwa