Eleventy (often referred to as 11ty) is a simpler static site generator (SSG) written in JavaScript that focuses on speed, flexibility, and a streamlined developer experience.

The principal functionalities of this tool include:

1. Exceptional Performance

• Blazing Build Speeds: It offers significantly faster build times compared to many other popular generators, such as Gatsby, Astro, or Next.js.

• Zero Client-Side JavaScript: By default, it produces static sites with no client-side JavaScript, ensuring optimal loading speeds and a solid foundation for progressive enhancement.

2. Unmatched Template Flexibility

• Multi-Language Support: It works with a wide variety of template languages—including HTML, Markdown, WebC, Liquid, Nunjucks, Handlebars, and even TypeScript—which can be used individually or mixed within a single project.

• Independent Content: It uses independent template languages, ensuring your content is not "held hostage" by a custom format, which facilitates much easier migrations if you ever decide to switch tools.

3. Seamless Developer Experience

• Zero-Config to Start: You can get a project running with virtually no initial configuration, though it remains highly extensible for advanced needs.

• Incremental Adoption: It can be integrated into existing projects to migrate only a few templates at a time, and it works with any directory structure you choose rather than forcing specific "app" or "pages" folders.

• Modern Tooling: It includes a built-in development server with live-reloading capabilities to speed up the local coding process.

4. Stability, Privacy, and Trust

• Production Ready: It is a stable, mature tool trusted by major organizations including NASA, CERN, Google, Microsoft, and the Louvre Museum.

• Privacy-First: Unlike many modern developer tools, it does not track users and contains no telemetry or mandatory data collection.

• Long-Term Stability: The project prioritizes stability; across hundreds of releases, only a handful have required manual changes from developers to maintain their sites.