HMPL (HyperMedia Presentation Language) and HTMX are two distinct template languages used for building dynamic web applications. While both share similar goals, they differ in their underlying concepts, syntax, and working mechanisms.

The key differences lie in the concept of the two modules. HMPL is a template language that relies on objects to build its framework, whereas HTMX is a set of tools that expand HTML's capabilities using tags, classes, and nesting.

In terms of syntax, HMPL uses an object-based approach, while HTMX employs tag attributes and nested constructions. When it comes to working with JavaScript, HMPL relies heavily on the language for processing requests, whereas HTMX allows developers to work more directly in HTML without needing to resort to JavaScript.

Another significant difference is the way each handles the real DOM. HMPL creates independent components that operate within a separate node or array of nodes, whereas HTMX works directly with the document's DOM and can search for targets throughout it.

Finally, HMPL uses fetch by default for sending requests, while HTMX defaults to XMLHTTPRequest, which provides support for older browsers but also has its drawbacks.

These differences highlight the unique strengths and limitations of each template language, allowing developers to choose the best fit for their project's specific needs.

Source: https://dev.to/antonmak1/differences-between-hmpl-and-htmx-1h25