Claude Usage Tracker is a Firefox extension designed to help users keep track of their Claude usage quota. It calculates token consumption from various sources, including uploaded files, project knowledge, chat history, and AI responses. The extension provides tooltips for most elements in the chat UI, offering further explanations on aspects like length, cost, estimate, and caching status. This makes it easier for users to understand their token usage at a glance.

The extension tracks token usage from files, projects, personal preferences, message history, system prompts, and certain integrations. However, it has limitations, such as not being able to track web search results accurately due to restrictions in accessing full results. Token calculation can be done through Anthropic's API or via gpt-tokenizer. Additionally, it synchronizes usage amounts across devices and stores data on token consumption to provide accurate counts.