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

#ai #opensource #productivity #showdev

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.

A rolling 5-hour session window
A weekly pool shared by all models
Separate weekly caps per model (Opus, Sonnet, Claude Design)

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.

What it does

It puts a color-coded % badge in your toolbar, and one click shows the full breakdown:

Current 5-hour session + live countdown to reset
Weekly all-models pool (with the Fable draw-down flagged on the card)
Per-model weekly caps: Opus, Sonnet, Claude Design
Daily Claude Code routine runs
Extra-usage credits + prepaid balance for pay-as-you-go
Auto-detects your plan (Pro / Max 5x / Max 20x / Team), so every number matches your subscription
Six themes

The privacy part (the part I cared about most)

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.