cheat - Cheat allows you to create and view interactive cheatsheets on the command-line.

MemberVault - MemberVault is a flexible platform that helps you to create, deliver, and sell your services, courses, memberships, subscriptions, etc.

cheat.sh - The only cheat sheet you need Unified access to the best community driven documentation

Ruzuku - Ridiculously easy online courses

explainshell - Match command-line arguments to their help.

Opentute - Opentute helps businesses to effortlessly launch a private eLearning and communication platform to engage teams and clients.