What is htmx?

Summary

htmx is a small, dependency-free JavaScript library that lets HTML attributes make HTTP requests and swap the HTML the server returns into the page. Any element can send a request, on any event, with any HTTP method, and update any part of the page, without writing JavaScript.

Longer Answer

You add attributes such as hx-get, hx-post, hx-target and hx-swap to ordinary HTML. When the element is triggered, htmx sends the request, receives an HTML fragment, and inserts it into the target. It works with any backend that returns HTML (Django, Flask, FastAPI, Rails, Laravel, Express, Go, ASP.NET) and needs no build step: one script tag.

Code Example

<button hx-get="/hello" hx-target="#greeting">Say hello</button>
<div id="greeting"></div>

Key Points

• A JavaScript library driven by HTML attributes.
• Server returns HTML, not JSON.
• Any element, event, method and target.
• Backend-agnostic, no build step.

Deep dive: htmx Tutorial: htmx Introduction

What interviewers look for

The core idea (HTML over the wire, attributes instead of JavaScript) and where it fits.

Follow-up questions

• How is it different from React?
• What does the server send back?