Filling device storage with HTML5 localstorage

HTML5_Logo_128A while back I wrote about using HTML5 local storage engine for storing websites data locally on a client device for caching or off line use. The W3 recommendation on web storage recommends a size limit on the amount of data storage allowed per origin. This has currently been implemented by the major browsers as follows:

  • 2.5 MB per origin in Google Chrome
  • 5 MB per origin in Mozilla Firefox, Safari and Opera
  • 10 MB per origin in Internet Explorer

The W3 recommendation also states “User agents should guard against sites storing data under the origins other affiliated sites, e.g. storing up to the limit in,,, etc, circumventing the main storage limit.”. But according to this site Safari, Chrome, Opera and IE don’t perform this check. With Firefox being the only one that is a bit smarter about the way things are handled, This allows a domain to have multiple sub domains redirect through them adding some local storage from each effectively filling the devices available storage.

All in all an interesting proof of concept which may be a sign of things to come. With some of the short comings by browser makers and their implementation of new HTML5 features.

Further Reading:

W3 web storage recommendations

Information regarding the Fill Disk POC

Leave a Reply

Your email address will not be published. Required fields are marked *