LLM Token Counter is a free, in-browser tokenizer that gives you exact tiktoken counts for OpenAI (GPT-4o, GPT-4, GPT-3.5, o1, o3) and accurate estimates for Claude, Llama 3, Gemini, and Mistral. See your prompt tokenized live with color-coded chunks, character/word/sentence/line counts, average chars-per-token per model, and sample prompts for quick testing. 100% client-side, no signup, no API key, no data leaves your browser. Works offline after first load. Free forever.