Solid reference for implementing JWT, OAuth 2.0, and API key authentication across Node.js and Python Flask. You get working middleware examples, a comparison table of auth methods with their security tradeoffs, and the critical security requirements like HttpOnly cookies and bcrypt cost factors. The code actually validates authorization headers properly instead of the naive split you see in too many tutorials. Use this when you're setting up authentication from scratch or debugging why your auth flow is failing. The security headers and common mistakes section will save you from the usual footguns like storing tokens in localStorage or logging sensitive data.
npx skills add https://github.com/secondsky/claude-skills --skill api-authentication