Hypermedia at Scale with Carson Gross (HTMX) | REST, HTMX 4, AI

Summary

Carson Gross explains how HTMX grew out of his preference for HTML-based, server-driven web applications over the JavaScript-heavy patterns popularized by frameworks such as Angular and React. He first built Intercooler.js, which combined behavior expressed through HTML attributes with Ajax requests that returned HTML to insert into the page. During the COVID period, he rewrote it without its jQuery dependency; that rewrite became HTMX.

Hypermedia, REST, and HTMX

Hypermedia combines content with controls for navigating or changing it. On the web, links and forms are familiar examples: they present content while also specifying actions and network requests.

Gross argues that a JSON response is data, not hypermedia. In Roy Fielding’s original account of REST, a RESTful system must use hypermedia controls. Gross says many APIs commonly called “RESTful” do not meet that requirement, and prefers the term JSON API for them.

HTMX extends the links-and-forms model. HTML attributes can specify when to issue an HTTP request, where to place the returned HTML, and how to update part of a page without a full reload. Examples include search-as-you-type, filtering, and infinite scrolling.

Gross says hypermedia suits many ordinary web applications, but is not a natural fit for experiences requiring very low latency and extensive local interaction, such as 3D games. He recommends keeping public-facing and government websites simple where possible. Building on core browser and web behavior can make them more durable and less dependent on changing frameworks or toolchains. Sometimes plain HTML is enough, without HTMX.

HTMX 4 and Related Tools

Gross describes HTMX 4 as a mostly internal cleanup, with a public API that remains close to HTMX 2. Changes he highlights include:

• Explicit attribute inheritance: In HTMX 2, attributes on a parent could affect its children implicitly. HTMX 4 requires inheritance to be marked explicitly, making behavior easier to trace in a codebase.
• Simplified history restoration: The behavior when returning to a page with the browser’s Back button is intended to reduce problems, including those caused by third-party JavaScript.
• Standardized event names to make event conventions more consistent.
• A move toward Fetch internally, replacing the older XHR-based implementation. Gross notes that XHR had some capabilities, such as load events for large transfers, that Fetch did not provide when he originally chose to retain it.

He also mentions Fixie.js, a deliberately minimal alternative of roughly 90 lines. It uses Fetch and offers a smaller subset of HTMX’s behavior, leaving more functionality to custom scripting.

AI, Education, and Engineering

Gross expects AI-assisted and “vibe-coded” development could make HTMX more specialized, partly because AI tools and their training data often favor React and its larger ecosystem. He still considers hypermedia worth understanding as an important web architecture, even if developers do not use it for every project.

His advice is to use AI as an aid rather than a substitute for technical judgment. AI-generated code can make poor architectural choices and accumulate shortcuts, so developers should review and understand what it produces.

As a computer science instructor, Gross has shifted away from treating programming assignments as the main evidence of mastery and toward in-person pencil-and-paper exams. Students may use a page of handwritten notes, which he believes encourages active learning. He also emphasizes visual teaching tools, including debuggers that show how high-level code relates to assembly and machine behavior.

Guides, Tutorials, and References

• Hypermedia Systems — Gross’s free online book. Its opening chapter demonstrates building a web application with conventional HTML links and forms; later material explains how HTMX addresses some limitations of that approach.
• HTMX examples — Suggested for seeing patterns such as live search and result filtering.
• HTMX essays — Gross points to essays on how REST came to mean something different from Fielding’s original usage, and to “Yes And,” an essay about advice for younger people entering technical careers.
• Teaching emulators — Gross mentions an online 16-bit teaching computer and a simpler 8-bit emulator for learning assembly and computer systems.
• Chesterton’s Fence — An engineering principle Gross applies to code changes: understand why an existing design is there before removing or replacing it.

Other books he recommends include A Philosophy of Software Design by John Ousterhout, The Master and Margarita by Mikhail Bulgakov, and The Brothers Karamazov by Fyodor Dostoevsky.

Main Speakers and Sources

• Carson Gross — Creator of HTMX and Intercooler.js; computer science professor at Montana State University.
• Neciu Dan — Interviewer and host of the Señor Developer podcast.
• Referenced sources: Roy Fielding’s dissertation on REST; Gross’s Hypermedia Systems and HTMX essays; John Ousterhout’s A Philosophy of Software Design; and G. K. Chesterton’s idea of Chesterton’s Fence.