Utilities

Online

Layout editors

KB Layout Editor V2

By ne0phyte

ne0.cc/laygenV2/

Keyboard Layout Editor

By ijprest

www.keyboard-layout-editor.com

Colour choosers

Keyboard color chooser

By matt3o

web.archive.org/web/20131010233322/http://lab.cubiq.org/kbcc/ (Wayback Machine)

Signature Plastics full keyboard colour preview

Computer software

Diagnostics

Switch Hitter

By EliteKeyboards
For Microsoft Windows; MSI installer

www.majorgeeks.com/files/details/switch hitter.html

Aqua's KeyTest

By Aqua of OTD
For Microsoft Windows; standalone executable

Geekhack thread