fast

FAST (Fluent Adaptive Styles for Templates) is an open-source interface system from Microsoft aimed at modern web experiences. Its core is @microsoft/fast-element, a lightweight library for building performant, memory-efficient, standards-compliant Web Components based on W3C Web Component specifications. These components run in every major browser and can be used alongside any front-end framework or without one at all, which makes FAST a good fit for incremental adoption in existing codebases rather than a full rewrite. The project also ships @fluentui/web-components, a ready-made component library built on fast-element and styled according to the Fluent design language. Its source lives in the Fluent UI monorepo. Together the two packages cover both ends of the spectrum: teams that want drop-in components can use the Fluent library directly, while teams that want to define their own design system can build custom components with fast-element. Key characteristics evident from the repository: - Framework-agnostic: components integrate with any library, framework, or build system, and the integration docs describe how to wire FAST into existing stacks. - Standards-first: built on native Web Components and modern web standards rather than a proprietary runtime. - TypeScript-based, with Prettier code style and CI workflows that validate pull requests and cross-platform/browser behavior. - MIT licensed, with an active community on Discord and GitHub, including labeled good-first-issues for new contributors. The README points users to a getting-started guide, integration documentation, a roadmap, and a contributor guide, and it frames the project around two entry points: consuming ready-made Fluent components or authoring your own with fast-element. Overall, FAST is best understood as a component-library and component-authoring toolkit for web developers who want reusable, portable UI built on open web standards.