Sätteri is a high-performance Markdown and MDX processing pipeline designed for the JavaScript ecosystem. Developed by the Bruits collective, it bridges the gap between fast Rust-based parsing and the flexible, plugin-driven nature of JavaScript development. By offloading the resource-intensive parsing and Abstract Syntax Tree (AST) management to a robust Rust core built on pulldown-cmark, Sätteri provides significant performance advantages while maintaining a familiar interface for developers accustomed to the JavaScript ecosystem.

The tool functions as a sophisticated pipeline that transforms Markdown and MDX content through two distinct stages: MDAST (Markdown Abstract Syntax Tree) and HAST (Hypertext Abstract Syntax Tree). Users can hook into either of these stages using TypeScript-defined plugins. This separation of concerns allows developers to apply logic where it is most appropriate, such as handling Markdown-level shortcodes in the MDAST stage or manipulating HTML attributes and structure during the HAST stage. The communication between the Rust core and JavaScript plugins is facilitated through napi-rs, ensuring low-overhead interactions.

Some of the key features are:

• High-Performance Parsing: Leverages a native Rust engine for rapid Markdown and MDX compilation.
• Two-Stage Plugin System: Supports transformation hooks at both the MDAST and HAST levels for precise control.
• Typed Plugin API: Offers a developer-friendly, type-safe API for creating custom transformations in TypeScript.
• Broad Feature Support: Includes opt-in support for GitHub Flavored Markdown (GFM), frontmatter, math equations, and directive containers.
• Multi-Runtime Compatibility: Ships with native binaries for macOS, Linux, and Windows, alongside a WASI fallback for browser and edge environments.
• Vite Integration: Provides a dedicated plugin, vite-plugin-satteri, to enable direct importing of .md and .mdx files into Vite-based projects.

To use Sätteri, developers install the package via standard package managers like npm, pnpm, yarn, or bun. For basic needs, the markdownToHtml function provides a straightforward API to compile strings into HTML with optional feature flags. For more complex requirements, users define custom plugins using defineMdastPlugin or defineHastPlugin, which are then passed to the compiler configuration. The native binary performs the heavy lifting, while the plugin logic runs within the JavaScript runtime, ensuring that existing tooling and workflows remain intact while benefiting from Rust's speed.

Some common use cases include:

• Static Site Generation: Building fast, efficient static site generators where quick build times are critical.
• Document Processing: Automating the transformation of Markdown documentation files into HTML for web-based knowledge bases.
• MDX Component Rendering: Integrating Markdown content with interactive JSX components in frameworks like React or Preact.
• Content Customization: Implementing custom plugins for specific syntax, such as emoji substitution, external link enhancement, or table of contents generation.