The answer depends on whether the extension is a content script or not.
If it's a content script, it runs within the page's origin, and so uses the page's localStorage
.
If it's not a content script, then according to this answer to a question about storage limits, yes, your extension gets its own local storage because its origin is chrome-extension://EXTENSIONIDHERE
. localStorage
is stored per origin, so your extension will have its own local storage.
As an alternative, as I mentioned in a comment, you can use chrome.storage
(available to content scripts and non-content scripts alike), which has options for syncing, can store objects rather than just strings, and various other advantages.