Token Watcher

About

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.

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WHAT IT TRACKS
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▸ 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

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WHY DEVELOPERS LOVE IT
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✔ 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

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FREE vs PRO
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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

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PRIVACY
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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.

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SUPPORTED SITES
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• claude.ai (all subdomains including a.claude.ai)
• chatgpt.com / chat.openai.com