ModelFusion

ModelFusion is a practical online toolkit designed for developers, researchers, and professionals working with large language models (LLMs). It provides a collection of free, interactive tools that help users manage the entire lifecycle of LLM usage—from cost estimation and model selection to prompt optimization and local deployment. The platform functions as a central hub where users can access accurate, up-to-date information and utilities without needing to navigate multiple sources. One core component is the LLM Cost Calculator. This tool allows users to estimate API expenses for models like GPT-4, Claude-3, Gemini, and over 30 other AI systems. Users input parameters such as token count, model type, and pricing tier, and the calculator returns a precise cost projection based on current rates. This helps developers budget for projects, compare service providers, and avoid unexpected charges. The calculator is updated regularly to reflect pricing changes from OpenAI, Anthropic, Google, and open-source providers. Another utility is the Prompt Tokenizer. It analyzes text inputs to show exact token counts and decomposition. This is important because LLM pricing often depends on token length, and many models have context windows that limit total tokens. The tool supports multiple tokenization methods (e.g., GPT-2, GPT-3.5, T5, Llama) and can highlight which parts of a string consume the most tokens. Users can test and refine prompts before sending them to an API, reducing wasted tokens and improving response quality. The Prompt Library stores a curated set of effective prompts for common tasks—such as code generation, data extraction, summarization, and question answering. Each prompt includes metadata like intended model, expected output format, and performance notes. U