Per Harald Borgen

CSS Flexbox: A Complete Guide [2026]

Every flexbox property explained with working CSS: main axis vs cross axis, flex-grow, flex-basis, the flex shorthand, layout recipes, and common gotchas.

Frontend Interview Prep Guide [2026]

The frontend interview questions asked in 2026, stage by stage: JavaScript, React, CSS, accessibility, and system design, with answers and a prep plan.

How to Test React Apps [2026]

React testing in 2026: Vitest, React Testing Library, user-event, MSW, and Playwright. Setup, components, async, hooks, and the mistakes to avoid.

React Router: A Complete Guide [2026]

A current React Router tutorial for v8: the three modes, nested routes, params, loaders, actions, protected routes, and migrating from v5, v6, and v7.

Best Full-Stack Developer Courses [2026]

Compare 12 full-stack courses on cost, length, stack taught, and certificate, grouped by learner situation. Free and paid options verified July 2026.

React 19: What's New for Developers [2026]

Every React 19 feature explained with code, verified against react.dev: Actions, the use hook, ref as a prop, the React Compiler, and what breaks.

Free AI Courses for Developers [2026]

14 free AI courses for developers, sorted by goal, with what each one costs and whether the certificate is free, paid, or does not exist at all.

How to Use Claude Code: A Developer's Guide [2026]

Learn how to use Claude Code in 2026: install it, run the explore-plan-code-commit loop, write a CLAUDE.md, set permission modes, and connect MCP servers.

How to Build REST APIs: A Beginner's Guide [2026]

Learn how to build a REST API from scratch: what REST is, the HTTP methods and status codes to know, a step-by-step build, and the mistakes to avoid.

Best Free TypeScript Courses [2026]

Compare 6 genuinely free TypeScript courses for 2026, ranked by depth, interactivity, projects, and certificate. Find the right free course for you.

Best Free SQL Courses [2026]

The best free SQL courses in 2026, ranked and reviewed by what they cover, where they stop, and who they suit, plus a quick way to pick the right one.

Best React Projects for Beginners [2026]

The best React projects for beginners in 2026, ordered as a difficulty ladder, each mapped to the React concepts it teaches. Build, don't just watch tutorials.