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

After installing you will see a new tab in Developer Tools. 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.

For Firefox users, you can grab the .zip file of the latest version from the GitHub releases page and load it as a temporary extension. Note that you may need to enable "Always Allow on localhost" in the extension settings.

The svelte-devtools extension requires your Svelte application to be compiled with the dev option set to true. If you're using SvelteKit, this is done automatically, outside of that you will need to set it manually.

This extension officially supports Svelte version ^4.0.0.

Clone this repository, setup and run the build script

git clone https://github.com/sveltejs/svelte-devtools.git
cd svelte-devtools
pnpm install
pnpm build

This will build the codebase and output all the required files in the build directory. To load the extension for development, follow these steps:

1. Navigate to the extensions settings page
2. Turn on the 'Developer mode' switch
3. Click 'Load Unpacked' and select the build directory

• This extension was initially created and developed by RedHatter