When comparing GrafX2 vs Pixly, the Slant community recommends GrafX2 for most people. In the question“What are the best pixel art / sprite editors?” GrafX2 is ranked 3rd while Pixly is ranked 14th. The most important reason people chose GrafX2 is:
GrafX2 is scriptable using the Lua language, which can be used to automate tasks and add new functionality to it. The script library features advanced color reduction and enhancement tools, [palette analysis](http://eab.abime.net/showthread.php?t=76519), and much more.
Ranked in these QuestionsQuestion Ranking
Pro Scriptable using Lua
GrafX2 is scriptable using the Lua language, which can be used to automate tasks and add new functionality to it. The script library features advanced color reduction and enhancement tools, palette analysis, and much more.
Pro Supports many file formats
GrafX2 supports many file formats, including the popular gif and png, but also importing and exporting from deluxe paint, degas elite, and various other editors using custom formats.
Pro Palette color cycling
GraphX2 being based on older 256 bitmap software has inherited some tricks that modern pixel editors do not have . One of them being the ability to cycle color palette and produce animations and effects with it.
Pro Free, open source, and cross-platform
GrafX2 is totally free to use, copy, and modify. It's available on Windows, Linux, Mac OS X, Haiku, AROS, MorphOS, SkyOS, Syllable, Mint, and a few more systems. Basically anything is supported by the SDL library.
Pro Very large number of tools and effects
Pro Supports tileset addition and extraction
Pro Has a great palette tool
You can create gradients from one color to another, work in either RGB or HSL color space, save and load palettes, sort and organize palettes, and even work on "color cycling" images.
Pro Supports animations
The program has a basic support for animation using frames in newer versions. Graphics can be cloned and copied between frames and changed slightly.
See here how to animate with GrapfX2 https://www.youtube.com/watch?v=Gnq6zBZOqoM
Pro Has a customizable UI with themes support
Theme UI style can easily be changed from settings including buttons and colors.
Pro Drawing constraint mode for vintage 8bits machine
The program is able to enforce the pixel constraints of old machines (C64, ZX Spectrum, Apple II, Game Boy Color, etc.)
For example, in ZX Spectrum mode, only 2 different colors can be used in a 8x8 pixel block.
Pro Allows you to continue your work even when not in front of your PC
This tool works on both phones and tablets that run Android, which is handy for when you do not have access to a PC.
Pro You can use reference images
You can work with a reference image on top of your art, or by its side.
Pro Offers color ramp generator
Pixly offers a color ramp generator that then exports directly into a custom palette.
Pro Color selector with different color systems
RGB, CMY, HSB, and a somewhat different HUSL.
Pro Color filters
Pro Live image tiling
The user can create tiles in Pixly and keep an eye on progress in real time.
Pro Standard and custom palettes
Pro Animation support
Even though this is a mobile tool, it's fully featured and even allows you to create animations.
Pro Transparency support
The user can make transparent sprites in Pixly.
Pro Mirroring support
In Pixly, the user can make symmetrical art with a mirror, or even go bananas setting up two or more mirrors at different angles at once.
Pro Supports onion skinning
Onion skinning is also called ghosting. It allows the user to see the past and previous frames, while editing the current frame. This way, the user can make decisions on how to create or change an image.
Pro Gestures that feel natural on touch screens
In Pixly, you can move the art around with two fingers (like in Google Maps) and change the brush/eraser size with a three-finger pinch.
Pro Layered projects
Con Dated look and feel
It looks like it was never supposed to be used in the modern world.
Con Lack of modern features
Some modern features that are necessary to do pixel art creation for game dev work are lacking.
Con No PC version
The PC version has not yet been released.