Remarkable is an extensible Markdown parser library that implements the CommonMark specification and supports GitHub Flavored Markdown through configurable rule presets. Its core architecture separates parsing into distinct inline and block rule pipelines, enabling targeted customization of text-level and structural syntax while maintaining consistent behavior across standard Markdown features.
The parser is built around a plugin-based rule system where individual syntax rules can be toggled, extended, or replaced by external plugins. A preset configuration system allows users to switch between strict CommonMark, full GFM, or custom rule bundles, while a typographic replacement engine post-processes rendered text to substitute plain punctuation with typographic equivalents. The library also exposes a syntax highlighting hook on fenced code blocks for integration with external highlighting libraries.
Beyond its core parsing capabilities, Remarkable provides automatic URL linking, extended syntax support for tables, footnotes, definition lists, and abbreviations, and configurable typographic enhancements. The documentation covers installation, preset switching, and plugin loading through chained methods for custom parsing and rendering behavior.