Currently, as explained in LiveReload section of the reference manual, Dev Tools support for live reload requires use of 3rd party browser extensions. The suggested extensions have been unmaintained for more than a few years now as evident by the last publishing dates and the activity in the appropriate repos:

• https://addons.mozilla.org/en-US/firefox/addon/livereload-web-extension/
• https://chrome.google.com/webstore/detail/livereload/jnihajbhpnppcggbcgedagnkighmdlei
• https://github.com/livereload/livereload-extensions
• https://github.com/twolfson/livereload-extensions

In addition to that, the linked livereload.com site itself is down, which apparently isn't a transient issue as wayback machine was last able to index it on Jun 10th.

With this in mind Spring Boot should IMO revisit live reload capabilities of Dev Tools module. Additionally, some other technologies that I've work with recently offer live reload capabilities without requiring browser extensions at all. Some examples of that are hugo and even IntelliJ IDEA. Both of these work by appending the script within the served HTML, which contains some code that updates the page when needed. Something like this would both improve the developer experience and also remove the requirement to use (unmaintained) 3rd party browser plugins.