Svelte Devtools от RedHatter271

Svelte Devtools is a Firefox extension for the Svelte javascript framework. It allows you to inspect the Svelte state and component hierarchies in the Firefox Developer Tools.

After installing you will see new tab in Firefox DevTools. This tab displays a tree of Svelte components, HTMLx blocks, and DOM elements that were rendered on the page. By selecting one of the nodes in the tree, you can inspect and edit its current state in the panel to the right.