Markdown profile

GFM for GitHub-style documents—without blurring the extras.

Strict GFM adds a defined set of extensions to CommonMark. MDLoom's GitHub Extended profile layers separately documented product features on top.

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MDLoom defaultVersioned extras

Strict GFM remains selectable when GitHub's formal specification—not every feature in GitHub's product—is the compatibility target.

Strict GFM 0.29

Five formal extensions to the CommonMark baseline

Tables

Task list items

Strikethrough

Autolinks

Tag filtering

The tag-filter extension describes how potentially dangerous raw HTML tags are filtered. MDLoom still applies its own complete sanitization and URL policy after rendering; the flavor is not the only safety layer.

GitHub Extended v1

Useful extras, recorded separately

MDLoom never calls these features part of formal GFM. They live in a curated, versioned extension allowlist.

Math

Inline and display expressions rendered with a pinned, resource-limited math pipeline.

Mermaid

Diagrams with text and complexity limits, sanitized browser SVG, static canonical-PDF output, and fenced-source standalone HTML.

Alerts

GitHub-style note, tip, important, warning, and caution blocks mapped to accessible semantics.

Footnotes and highlight

Curated browser features that remain explicitly outside formal GFM and may map differently in rich exports.

Portability

Check extensions before leaving GitHub-like destinations

Tables and task lists are widely implemented but not universal. Math, alerts, Mermaid, and footnotes vary more. The profile dry-run compares browser semantics and diagnostics; each converter page separately states its known destination limitations.

When a destination cannot represent an extension, simplify the source, choose a static fallback where the workflow supports one, or select another output. Review the returned server warnings because the current UI does not claim a complete per-node compatibility planner.