Hey HN! Creator here.

I launched this as a SaaS earlier this year, failed to gain traction. Realized I was solving MY problem but not explaining it clearly.

So I'm open sourcing it with a better pitch:

The problem: I had 20+ Tampermonkey scripts for one-off tweaks. Maintaining them sucked. Writing new ones for simple stuff felt like overkill.

The solution: Chat interface where you describe the change, AI generates CSS/JS, applies it instantly.

Daily use cases: - "Dark mode this page" - "Hide YouTube shorts" - "Remove paywalls" (yes, controversial) - "Add keyboard shortcuts"

Technical stuff: - Your API key (Claude/GPT/Gemini/Grok/OpenRouter) - Smart DOM selector with stability scoring (checks for stable IDs, attributes like data-testid, role, aria-label before falling back to classes or nth-child) - Handles Shadow DOM, SPAs, dynamic content - Cloud sync via Supabase (optional)

GitHub: https://github.com/kchander/magix-extension Chrome Store: https://chromewebstore.google.com/detail/magix/ebfhenlkpdngc...

The hard part wasn't the AI - it was making modifications survive page updates. Uses Chrome's UserScripts API (Chrome 138+) to register scripts persistently, handles dynamic content injection, and manages script lifecycle across navigations. Lots of MutationObserver shenanigans for elements that get swapped out by SPAs.

See ya! Also my first open source project :)