This is a simple colour slider written in Microsoft Visual Basic, with support for HTML colour codes.
You can download the executable from https://github.com/pmachapman/RGB/releases/download/2.9/RGB-2.9.zip
As this is a program for programmers, you should only use if you know what you are doing! Be careful where you first run the program, and make sure you run it as Administrator if this is the first time you have run a Visual Basic 4 program on your computer. It will automatically register COMCTL32.OCX in the program directory. If you do not want this to happen, you should relocate the VB40032.DLL and COMCTL32.OCX files to your SYSTEM32 or SYSWOW64 directories, and run REGSVR32 on COMCTL32.OCX.
Use at your own risk!