Default Editor
Navigate to http://localhost:8080/ruleset.html or wherever your engine is hosted.
IDE Plugins
VS Code Plugin
There is a VS code plugin that gives diagnostics, completion suggestions, and allows you to register rulesets with a pico engine.
It can be found here.
Testing Tools (node pico engine)
Python module for interacting with Picos: https://github.com/hitch-b24/picosapi/wiki from Braden Hitchcock
Editor Plugins (classic KRL)
KRL Syntax Highlighting for Sublime from Ben Draut
KRL Validator for Sublime from Trevor Dixon
if you create a plugin for the current KRL language, please let Phil Windley know so we can list it.