I built a free extension to track Claude's usage limits before you hit them

A developer built Claude Usage Monitor, a free open-source browser extension for Chrome and Firefox that displays Claude's usage limits as a color-coded badge in the toolbar. The extension runs entirely locally with permissions scoped to four specific claude.ai endpoints, ensuring it cannot read chats or files. It tracks multiple limits including the weekly pool, where Fable draws the shared pool about twice as fast as Opus.

If you use Claude daily, you've probably hit a wall mid-task. The reason it's so easy: Claude doesn't have one limit. It has several. And the weekly pool is sneaky: Fable has no cap of its own and draws that shared pool down ~2× faster than Opus . So you can burn the week without realizing it. I wanted that state visible at a glance instead of digging through settings, so I built Claude Usage Monitor — a small browser extension for Chrome and Firefox. It puts a color-coded % badge in your toolbar , and one click shows the full breakdown: It's open source MIT and runs 100% locally — no backend, no analytics, no servers. A design decision I'm happy with: the host permissions are scoped to exactly four claude.ai endpoints org list, usage stats, routine-run budget, prepaid balance . It physically can't read your chats, projects or files. Narrow permissions = less to trust, and less to exploit. One honest caveat: it reads claude.ai's own usage endpoints, so it can break if Anthropic changes them. Not affiliated with Anthropic. It's free, no account needed desktop Chrome & Firefox : Happy to hear what else you'd want tracked — drop a comment.