What is HMPL?

HMPL is a lightweight JavaScript library that lets you build server-driven user interfaces without the overhead of a full frontend framework. Instead of shipping complex client-side logic, you define templates on the server and let HMPL handle the rendering. It uses a block-based syntax, customizable fetch requests, and built-in support for forms, events, and time-based syncing — all in just a few kilobytes. HMPL also integrates with JSON5 for expressive object syntax and DOMPurify for safe HTML rendering, making it a practical choice for developers who want dynamic interfaces without heavy dependencies.

Who it's for

• Backend-focused developers who want to control UI logic from the server without writing extensive client-side JavaScript.
• Teams building lightweight web apps that need dynamic content updates, form handling, and event-driven interactions without adopting a full SPA framework.
• Developers optimizing for performance who prefer a minimal client-side footprint and want to reduce bundle size while still delivering responsive interfaces.

Key features

Block-based template syntax

HMPL uses a clean, readable block syntax that lets you define reusable UI components directly in your server-rendered HTML. This approach keeps your templates organized and makes it easy to update content without touching client-side code.

Customizable fetch requests

You have full control over how HMPL fetches data from your server. Configure headers, methods, and endpoints per template block, so each part of your page can pull from different sources or APIs as needed.

Built-in form and event handling

HMPL handles form submissions and user events natively, without requiring additional libraries. You can bind actions to clicks, submits, or custom events, and let the library manage the communication with your server.

Time-based syncing

Keep your UI in sync with the server on a schedule. HMPL supports interval-based updates, so you can refresh specific parts of the page automatically — useful for dashboards, live feeds, or any content that changes over time.

What stands out

HMPL gives you server-driven UI without the framework tax.

Most solutions for server-driven interfaces come with a heavy client-side library or a complex build process. HMPL flips that by keeping the client lean — just a few kilobytes — while still offering features like form handling, event binding, and scheduled updates. It integrates JSON5 for cleaner object syntax and DOMPurify for security, so you don't have to bolt on extra tools. The result is a practical, no-nonsense approach to building dynamic pages that stays out of your way.

Worth checking out if…

You want to build dynamic, server-driven interfaces without committing to a heavy frontend framework. HMPL is especially useful if you're comfortable controlling UI logic from the backend and prefer a minimal client-side footprint. It's a solid fit for projects where performance and simplicity matter more than a rich ecosystem of client-side components.