Open source
The A11Y Project
Community guide to making websites accessible
Design A11y PerfCommunity accessibility guide
Alternatives to WCAG Quick Reference
12 tools like WCAG Quick Reference, chosen by what they do. About WCAG Quick Reference
Freemium
Every Layout
Guides on CSS layout that let the browser do the work
Design A11y PerfRobust CSS layout primitives
Paid
Interaction Design Foundation
Online UX, UI and AI design courses with certificates
Design A11y PerfUX and design courses
Free
Web Almanac
Yearly report on how the web is built, using HTTP Archive data
Design A11y PerfYearly state of the web
Paid
Nielsen Norman Group
UX research, training courses and guidance for design teams
Design A11y PerfUX research and guidance
Paid
Refactoring UI
Design tactics for developers who want to improve their UI
Design PrinciplesUI design tips
Open source
QuickRef.ME
Developer cheat sheets for languages, tools and shortcuts
Cheat SheetsQuick reference cheat sheets
Free
Python Documentation
Official reference, tutorial and guides for the Python language
Docs TutorialsOfficial Python docs
Curated
Devhints
Short developer cheat sheets for languages, libraries and tools
Cheat SheetsDeveloper cheat sheets
Curated
Docker Docs
Official guides, manuals and CLI reference for Docker
Docs TutorialsOfficial Docker documentation