There is a new extension that is very useful for seeing and clearing localStorage, en mass. It is Foundstone HTML5 Local Storage Explorer.
What's good about it is that it shows all localStorage
for every site -- not one site at a time like the other answers to this Q (so far).
Unfortunately, it does not provide an easy way to add or edit localStorage
values, but that's not too hard in Firefox, anyway.
To Add, Edit, or Delete individual localStorage values in Firefox (Firebug is not needed):
Navigate to the domain in question, for example: http://stackoverflow.com .
Open Firefox's console (Ctrl Shift K in windows).
Set a value like: localStorage.foo = "bar"
.
Or use localStorage.setItem ("foo", "bar").
Change a value like: localStorage.foo = "all day"
.
Or use localStorage.setItem ("foo", "all day")
.
Delete a value like: localStorage.removeItem ("foo")
.