Style Dictionary is a design token build system that transforms platform-agnostic design tokens into platform-specific output files. It is a Node.js library with a CLI entry point, designed to be the single source of truth for styles across web, mobile, and native platforms. The architecture is config-driven: users define a configuration with source token files (JSON, JSON5, JSONC, JS) and platforms, each specifying transform groups, filters, formats, and output files. The core pipeline loads tokens, preprocesses them, expands composite object tokens (e.g., border, typography), applies attribute/name/value transforms, resolves references (aliases), filters tokens, formats them using built-in or custom format functions, and writes the output files. The system supports extensive customization through hooks: transforms, formats, filters, actions, parsers, preprocessors, and file headers. It also provides utilities for reference resolution, color conversion (hex, RGB, HSL, OKLCH, P3, LCH), deep merging, and token data conversion. The library is designed to work both in Node.js and in the browser via an in-memory filesystem abstraction. Key entry points include the CLI (`bin/style-dictionary.js`), the main class (`lib/StyleDictionary.js`), the registration system (`lib/Register.js`), built-in transforms (`lib/common/transforms.js`), built-in formats (`lib/common/formats.js`), format helpers (`lib/common/formatHelpers/`), and reference utilities (`lib/utils/references/`). External dependencies include `tinycolor2` and `colorjs.io` for color math, `prettier` for code formatting, `chalk` for console output, and `deepmerge` for merging configurations. The codebase is well-tested with unit tests, integration tests, and snapshot testing, and it maintains compatibility with the Design Tokens Community Group (DTCG) draft specification. The project is actively maintained with recent commits, a changelog, and semantic versioning.