Markprompt is a tool that allows users to quickly and easily build a GPT-4 prompt for their Markdown docs. It eliminates the need for configuration, hosting and metrics collection. It works with Markdown, Markdoc and MDX files, and all OpenAI completion models are supported, including GPT-4. It offers a generous free-tier, and users can scale with usage. It also offers features such as feedback and analytics to help pinpoint shortcomings in content. The source code is available on GitHub.