Markdown is meant to read as plain text and also render into properly formatted output, but the gap between those two things is easy to fall into without noticing, a missing blank line before a list, indentation that's a space off, and the syntax looks fine sitting in a plain text editor right up until it renders as a single unbroken paragraph instead of a list. This tool shows Markdown source and its rendered preview side by side in real time, and exports the result to HTML, PDF, or formatted text ready to paste elsewhere. Useful for catching a markdown syntax mistake the moment it breaks rendering rather than after publishing, writing documentation that needs to become both a webpage and a shareable PDF from the same source, or drafting formatted content that needs to be copied into a rich text editor as properly styled text.