This is the list of software used to build our RealCW resource pack:
Adobe® Photoshop® & Adobe® Illustrator® (https://www.adobe.com/), the big monsters!
Paint.Net (https://www.getpaint.net/) always came in handy (available now also on Microsoft Store).
GIMP 2 (https://www.gimp.org).
Visual Studio 2015/2017 (https://www.visualstudio.com/) to create custom c# programs to compare resource packs, create batches of operations, optimize compression and to perform few other optimizations and validations.
Adobe Photoshop & Adobe Illustrator are trademarks of Adobe. VISUAL STUDIO is a trademark of Microsoft Corporation.