Token Watcher

Real-time MCP call and Token cost monitor for AI developers using Claude, Cursor, and Claude Code.

Track your Claude & ChatGPT token usage in real time. See input/output/cache costs, model breakdown, and MCP call health — right in your browser. Stop guessing what your AI conversations cost. Token Watcher is a lightweight Chrome extension that intercepts Claude.ai and ChatGPT requests to give you real-time visibility into token usage and API costs — no API key required, no external servers. ────────────────────────────── WHAT IT TRACKS ────────────────────────────── ▸ Input tokens, output tokens, cache write & cache read tokens ▸ Per-call cost calculated against current Anthropic and OpenAI pricing ▸ Cumulative daily / weekly costs with a 7-day bar chart ▸ Per-model breakdown — see exactly how much Opus vs Sonnet vs Haiku is costing you ▸ MCP (Model Context Protocol) call health — total calls, error count, error rate ▸ Works on Claude.ai (including the a.claude.ai streaming iframe) and ChatGPT ────────────────────────────── WHY DEVELOPERS LOVE IT ────────────────────────────── ✔ No API key needed — works directly on the Claude.ai and ChatGPT web UIs ✔ Captures exact token counts when available, estimated counts otherwise (marked with ~) ✔ Supports prompt caching metrics (cache_creation_input_tokens / cache_read_input_tokens) ✔ Model-aware pricing — Opus, Sonnet 4/3.7/3.5, Haiku 4.5/3.5/3, GPT-4o, GPT-4, GPT-3.5, o1, o3 ✔ Zero data leaves your browser — everything stored locally via chrome.storage ────────────────────────────── FREE vs PRO ────────────────────────────── FREE: • Real-time token + cost display • 7-day daily trend chart • Per-model breakdown • MCP call health monitoring PRO (via Gumroad license key): • Full 30-day monthly history • CSV export for billing & reporting ────────────────────────────── PRIVACY ────────────────────────────── Token Watcher does NOT: ✗ Send any data to external servers ✗ Require an Anthropic or OpenAI API key ✗ Store conversation content — only token counts and costs All data stays in your browser's local storage. ────────────────────────────── SUPPORTED SITES ────────────────────────────── • claude.ai (all subdomains including a.claude.ai) • chatgpt.com / chat.openai.com