Browser-based, HTML5 pixel art editor, with Wacom tablet support (requires a plugin, which has limited browser+OS support) and collaboration features.
Ranked in these QuestionsQuestion Ranking
Pro Offers Colordex system
Included in Pixel.Tools is the Colordex system which allows the user to utilize multiple color ramps in a single brush stroke.
Pro Record and replay
Pro Pixel with others simultaneously
Pro Wacom tablet support (via plugin)
Pro Free and open source
Pixel.Tools is licensed by MIT, making it free of charge and open source.
Con Unintuitive interface
Zooming is reversed, the screen flickers a lot, and the flip/rotate selection is very buggy (selection will re-size though it should not). Essentially, the interface of Pixel.Tools is clunky and unintuitive.