ContextMeter – AI Context Window & Token Counter

ContextMeter shows how much of the AI context window your current chat has used, so you know when to start fresh before answers get worse. What you get - A small meter on ChatGPT and Claude with the percent used, color-coded green, amber and red. - A details panel: estimated tokens, room left, and which messages take the most space. - Honest labels: every number is an estimate of the visible messages, and it says so. - Handoff: ask the AI for a structured summary, then continue in a fresh ChatGPT or Claude chat with one click. You press Send yourself. - Draft preview: see what an unsent paste would cost before you send it. - Reads your plan and model from the page: it detects your ChatGPT plan (Free, Plus, Pro) and shows the model, so the meter uses the right window. - Works on long chats: Claude removes older messages from the page as you scroll, so ContextMeter remembers what it has seen and offers a full-chat scan. - Settings for your plan or a custom limit, warning levels, theme and position. Keyboard shortcut: Alt+Shift+M. Private by design Everything runs on your device. No account, no analytics, no servers, no network requests. Chat text is never stored; only chat titles, message ids and token counts are kept on your device. Good to know - Counts are estimates: they cover visible message text, not system prompts, memory, tool output, hidden reasoning or attachments. - Context limits vary by plan and change often. ChatGPT starts on the Free plan; check yours in Settings. - ContextMeter is not affiliated with OpenAI or Anthropic.pro