This repository is the Javascript version of SOGL (that repository is really old though) - the online interpreter and the compressor are available on GitHub pages. Explanation of SOGLs characters is here and the interpreters code is found here. The interpreter mostly still works in Processing Java.
SOGL is a very weakly typed language, meaning that every function will do something for all types of input.
For example, 05AB1E has a function u for uppercasing and î for ceiling, but SOGL has one for both - U.
You'll never need to uppercase a number and take the ceiling of a string, will you?
This makes the language very complex, but makes many more free characters available.
Kolmogorov-complexity and ASCII-art art seem to be SOGLs strong side, but there still are remains of the times this was supposed to be all-purpose.
To make it easier to type SOGL characters, I've made a SOGL keyboard that uses AutoHotkey.