Grip is a Python-based command-line tool that renders local Markdown files using GitHub's Markdown API, ensuring the preview matches GitHub's exact styling. It serves as a local server, allowing instant browser updates without page refreshes. Key features include exporting to HTML, support for user-content rendering, and customizable configurations like port and host settings. Grip also offers API access for integration into other projects and supports authentication to bypass GitHub's rate limits. Ideal for Readme-driven development, it provides a seamless way to preview and refine documentation before pushing to GitHub.