Permissions

Chrome shows a permissions prompt at install. This page lists every item the extension declares in its manifest and what it does with each one. Nothing else is requested, and no permission is asked for later.

PermissionUsed for
alarmsScheduling the hourly filter-list refresh so rules stay current between releases.
activeTabIdentifying the site in the active tab, so a click on the toolbar icon applies to the right one.
tabsMatching a held-back pop-up to the tab it came from, and opening it in a background tab if you ask for that.
storageSaving your allowed list, the sites you have trusted for pop-ups, and the filter data the extension keeps on your device.
unlimitedStorageHolding the filter lists, which are larger than the default storage quota allows.
declarativeNetRequestApplying network rules so ad requests are stopped before they load. Chrome matches these rules itself; the extension does not see the requests.
webRequestObserving request outcomes to keep the toolbar state and the blocked count accurate.
scriptingInjecting the cosmetic rules and the pop-up prompt into the page.
<all_urls>Host access to every site. Filtering has to run wherever you browse, so the extension cannot be limited to a fixed list of domains.

What the extension does with data handled under these permissions is described in the privacy policy.