Evaluate markdown renderer

[spliffone]

Decision / evaluation criteria

• Theming support: The renderer should not ship with heavy, opinionated CSS or fixed styling. It must allow for easy overrides using Siemens Element’s design tokens (CSS variables) or provide style hooks.
• Framework: Element is intended to be used across different environments. The renderer should ideally be based a vanilla JavaScript library or provide a Web Component wrapper. We should avoid to introduce another framework dependency beside Angular.
• Syntax highlighting extensibility: Provide mechanism for code block highlighting.
• GFM (GitHub Flavored Markdown) Compliance: Support for modern standards like tables, task lists, strikethrough, and autolinks.
• SSR (Server-Side rendering) Support: The renderer must be able to run in a Node.js environment without access to the window or document objects.
• TypeScript support: The library must provide high-quality, up-to-date Type Definitions (@types) to ensure type safety within the development workflow.
• Tree-shaking and modularity: Is it possible to import only the parser and specific extensions (e.g., tables, task lists) to minimize the impact on the final bundle size?
• Math and diagrams: Support for extensions like KaTeX (for mathematical formulas) or Mermaid.js (for charts), which are often required in industrial and engineering documentation.
• HTML sanitization: A critical security criterion. The renderer must either include a built-in, robust XSS sanitizer or integrate seamlessly with DOMPurify to prevent malicious code injection.
• License compliance: MIT, Apache 2.0, or BSD. Avoid "copyleft" licenses (like GPL) that could complicate the distribution of proprietary software.
• Maintenance and security: Check the frequency of updates and the speed of patching CVEs (Common Vulnerabilities and Exposures). A library with zero-dependency or a small dependency tree is preferred.
• A11y conform: Ensures the generated content meets WCAG standards.
• ECMAScript modules bundle: ESM allow modern build tools to perform static analysis to detect unused code and "shake it out"

Alternative

• Only focus on syntax / code block highlighting e.g. by using highlight.js, prismjs or lowlight
• Find a good AST Markdown parser e.g. commonmark.js
• Go with the current PR which add all requested features: feat(chat-messages): add support for syntax highlighting, copying and downloading csv to markdown renderer #1158

Candidates

	marked + marked-highlight	markdown-it	showdown	micromark	remark
Last release
Last release date
Last commit
Weekly downloads