HMPL.js is a lightweight server-oriented template language designed specifically for JavaScript applications. Its main purpose is to provide developers with the flexibility to build server-driven templates while maintaining minimal JavaScript footprint, allowing for dynamic user interfaces without relying on heavy frameworks.

The template language offers block-based syntax for structured templating and supports customizable fetch requests for flexible server interactions. It includes built-in support for forms, events, and time-based syncing capabilities. HMPL integrates with JSON5 for expressive object syntax and DOMPurify for safe HTML rendering, ensuring XSS protection.

HMPL.js operates using a combined format approach where developers use minimal code to fully customize server requests while maintaining interaction with templates. This server-oriented architecture allows handling numerous use cases efficiently while keeping the bundle size small at approximately 24KB gzipped.

The language provides benefits including extensive server functionality in a compact package, 100% code coverage for reliability, and protection against XSS vulnerabilities. It enables developers to get ready HTML from the server by describing only a couple of properties in an object, making it easy to implement.

HMPL.js targets JavaScript developers looking for lightweight templating solutions and serves as an alternative to HTMX and Alpine.js. It integrates with various platforms and frameworks while maintaining compatibility with modern ECMAScript features and supporting HTTP methods including OPTIONS and TRACE.