Claude Monitor shows how much Claude you have left before you hit a usage limit. A badge in your browser toolbar tracks your 5-hour session and weekly limit live, with a countdown to every reset and desktop alerts at 80% and 95%. One click opens the full picture: per-model weekly caps, extra-usage credits in real money, Claude Code routine runs and 30 days of history you can export to CSV or JSON.

Turn on the optional bar and the limits sit right above the claude.ai chat box. It also works on the Free plan: since August 2026 claude.ai shows no usage to Free accounts, so the extension reads the message_limit event from each reply's stream instead.

How it is built: a Manifest V3 extension for Chrome and Firefox, in plain JavaScript with no build step. It reads the same usage endpoints claude.ai's settings page uses, read-only. The page scripts for the bar use optional permissions, requested only when you turn the bar on and released when you turn it off.

Free, open source (MIT), no account, no telemetry, no servers. Nothing leaves your browser. Not affiliated with Anthropic.