markdown-it
Markdown parser, done right. 100% CommonMark support, extensions
...It also supports plugins that extend functionality, such as adding emoji support, footnotes, or custom containers, enabling highly tailored rendering pipelines. markdown-it emphasizes security by default, ensuring that generated HTML is safe for use in web environments without introducing vulnerabilities. Its architecture balances speed and extensibility, making it suitable for both lightweight applications and large-scale content systems.