Tokenizer Live Token and Cost Monitor is a free Chrome add-on designed to enhance user experience in AI chat interfaces by providing real-time insights into token usage and associated costs. This tool is compatible with various AI models, including ChatGPT, Claude, Gemini, and more, allowing users to monitor their interactions seamlessly. The overlay displays live token counts, cost estimates for both input and output tokens, and a cumulative session total, all without any setup requirements.

One of the standout features of Tokenizer is its ability to compare costs across different AI models for the same prompt, enabling users to make informed decisions. Additionally, it offers a detailed word-level token breakdown, highlighting which words consume the most tokens. For environmentally conscious users, it provides energy usage estimates, detailing the approximate watt-hours and CO2 emissions per prompt. As an open-source tool, it ensures privacy by operating entirely locally in the browser without data collection.