Putting It All Together

You've built every layer:

Production parsers:

• CommonMark.js: reference implementation, ~600 test cases
• markdown-it (JS): popular, plugin-based
• marked (JS): smaller, fast
• pulldown-cmark (Rust): blazing fast
• Goldmark (Go): standard for Hugo
• Markdig (.NET): for Razor pages
• Python markdown, mistune: Python options

You should USE one, not write your own — the spec is full of edge cases. Building one is an excellent learning exercise (this course!).

What's NOT in CommonMark:

• Tables (GFM)
• Strikethrough (GFM)
• Task lists (GFM)
• Auto-link (with detection): https://... → link
• Footnotes
• Definition lists
• Math (LaTeX)
• Mermaid

Each renderer adds these as extensions.

Where you've seen Markdown:

• README files (GitHub, GitLab, npm)
• Static site generators (Hugo, Jekyll, Eleventy)
• Documentation (Sphinx, MkDocs)
• Blogging (Ghost, dev.to)
• Discord, Slack, Reddit (subset)
• Notion, Obsidian, Bear (variants)

You now understand the foundation.