HTMX

HTMX is a small (14k min. gzipped), dependency-free javascript library that can create cutting-edge user interfaces with the ease and power of hypertext (markup). It provides access to AJAX, CSS Transitions, WebSockets, and Server Sent Events directly in HTML using attributes. This has become a game-changer for developers as it enables them to achieve interactivity (that JavaScript gives) from the markup alone.

https://lassebomh.github.io/htmx-playground/

Why Gumroad Didn't Choose htmx - https://htmx.org/essays/why-gumroad-didnt-choose-htmx/