If you are a user of Photoshop, Photopea is super easy to use and it is full featured.
As a GIMP user, I had to do my usual tinkering around. But aside from the usual trips to the FAQs to figure out how to use some of the tools, it wasn't hard.
The tutorials are very good. There are only a few of them, but they are nice to have.
The FAQs are excellent. The FAQs are excellent because the Develops respond to questions. Seriously. They actually pay attention to the comments and respond. I know, right? There should be some kind of dev award for that.
Go ahead, give the free version a whirl. If you like it and want to get rid of the ads or just support the developer, you can upgrade to the paid version. The free version is great and the only tool you can't use is converting Sketch to PSD (no other program does that), which most people do not need.
Very, very cool online app! Click on the image to get to the app!