Storage API - some websites want to add files to my computer
Some websites have the ability to store information, such as files, in your local storage, and these files can only be removed manually by you. This helps the website run faster and prevents information from being lost if you lose your connection. This feature is enabled by storage API.
When a website has storage API, Firefox will first ask you for permission to let a website add files to your local storage.
When the prompt appears in your address bar, choose “Allow” or “Don’t Allow”.
What if my storage is full?
You’ll see a prompt at the top of the page letting you know that your storage is full. Click the button to manage your storage. Freeing up space on your disk by deleting files can also free up storage for Firefox.