GIMP
Open Source
GIMP stands for GNU Image Manipulation Program which is an opensource image editor program supporting almost every popular image formats.
Gimp Paint Studio
Open Source
GIMP Paint Studio is a great pack of designing components like brushes, dynamics, gradient etc.
Photopea
Free
Photopea is a free online image editor, that runs without plugins. It can both read and save PSD files.
Compare Sumo Paint with alternatives
Compare Photopea and Sumo Paint and decide which is most suitable for you.
Compare Gimp Paint Studio and Sumo Paint and decide which is most suitable for you.