Prompt Token Counter is an online prompt token calculator that helps users in real time calculate the number of input tokens when using large language models, to manage usage costs and comply with model limits.
The tool supports a range of mainstream LLMs, including OpenAI's GPT series, Claude, Gemini, and Llama, and provides token limit references for each model.
According to the site, the core online token counting feature is available for free. The site also mentions a professional prompt optimization service, which is paid.
The tool accurately counts prompt tokens and combines model pricing information to provide an estimated API call cost, helping with budgeting and decision-making.
The tool aims to estimate using tokenization algorithms similar to those used by official models. However, actual token usage in API calls can vary by implementation and context; results are for reference only.
According to its description, the tool primarily counts tokens for text content. For multimodal content (such as images), it may provide estimated reference values, but actual consumption should be based on API responses.
There are two main reasons: first, all models have a maximum input context length, and exceeding it may cause truncation; second, API costs are typically based on the total number of input and output tokens.
According to the site, the professional service package includes requirements analysis, prompt optimization, improved documentation, best-practice guides, and a period of monitoring dashboards, with a delivery cycle of about three weeks.
Prompt AI provides a systematic guide to prompt engineering, helping users quickly design and optimize prompts, enabling large language models to get it right on the first try, save costs, and ensure safety.

PromptLayer is a collaboration platform for AI engineering teams, specializing in the development and operations of large language model applications. It provides a full lifecycle toolkit—from prompt management and workflow orchestration to monitoring and optimization.