DevTools

Detailed Explanation

DevTools (Developer Tools) is a set of Debugging tools built into every modern browser (Chrome, Firefox, Edge, Safari). They let you inspect your Web Application in real time — see the HTML structure, CSS styles, JavaScript errors, network requests, and more.

To open DevTools, press F12 (or right-click → Inspect) in your browser. You'll see several tabs:

• Console: Shows JavaScript errors, warnings, and your console.log() output
• Network Tab: Shows every HTTP Request your app makes (to Supabase, APIs, etc.)
• Elements: Shows the live DOM tree and CSS styles
• Sources: Shows your JavaScript source code for breakpoint debugging

For fullstack development with React and Supabase, the Console and Network Tab are your most important tools. The Console shows runtime errors and your Logging output, while the Network Tab reveals exactly what data your loaders and actions are sending and receiving.

DevTools is not something you install — it's already in your browser. Learning to use it effectively is one of the most important skills for any web developer, and Claude Code can help you interpret what you see there.