Browser Extension Permission & Risk Monitor

An extension you installed last year can ask for more power in its next update, and nothing in the browser tells you. This Actor reads what Firefox add-ons actually request — permissions, site access and declared data collection — scores the risk, and reports when those permissions last changed.

Built on Mozilla's public add-ons API. No key, no login, no scraping.

What makes it useful on the first run

Most "monitors" can only tell you about a change after they have seen the thing twice. Mozilla publishes permissions per version, so this one reads the version history and reports the last permission change immediately — which version added what, and when.

Example from a live run: Tampermonkey — last permission change in v5.5.0 (2026‑05‑21), added contextualIdentities. No second run required.

Risk scoring, and why you can trust the number

The score is a published formula, not a black box. It ranks what an extension could do:

Signal	Points
Access to every website (<all_urls>, *://*/*, http://*/*, https://*/*)	40
nativeMessaging — can hand data to a program outside the browser	25
proxy — can route all your traffic	25
debugger — can drive any page	25
webRequestBlocking — can rewrite traffic in flight	15
webRequest, cookies, history, management	10 each
clipboardRead	8
browsingData, bookmarks, downloads, privacy, identity, geolocation, topSites	5 each
tabs, scripting	3 each
Each declared data-collection type (other than "none")	10 each
Access to named sites only (not the whole web)	1 each, capped at 10

low under 20 · medium 20–49 · high 50+. riskReasons spells out what drove the number.

A high score is not an accusation. uBlock Origin scores 73 because a content blocker genuinely needs to see every request — and it is Mozilla-recommended, which the output also tells you (isRecommended). The score measures capability; you supply the judgement about whether this extension should have it.

Monitor mode

changeType	Means
permissions_added	It now asks for something it did not before — the event this exists for
permissions_removed	It gave something up
version_change	New version, same permissions
risk_change	The score moved for another reason
new	First time seen in this scope
unchanged	Nothing moved

Input

Field	What it does
Extensions	Slugs, full addons.mozilla.org URLs or GUIDs — paste whatever you have.
Search query / Category / Sort	Discover extensions instead of naming them.
Minimum daily users	Useful when auditing what an organisation actually runs.
Detect the last permission change	Reads version history. One extra request per extension.
Monitor mode / Output only changed	The alert behaviour above.

Notes & limits

Properties of the source, measured rather than assumed:

• Site access hides in two different fields. Under manifest v2 host permissions sit inside permissions; under v3 they move to host_permissions. In the top 50 add-ons <all_urls> appears in permissions 28 times and in host_permissions only 4 times — so reading just the v3 field would miss full-web access on most extensions. Both are read and merged.
• "Declares nothing" and "declared none" are different, and both appear. ["none"] is an explicit promise to collect nothing; an empty or absent field is simply no declaration — 41 of the top 50 have none at all. declaresDataCollection is true only when something was actually declared, so silence is never reported as a promise.
• Permission counts vary wildly: median 13 in the top 50, maximum 397. A long list is not automatically dangerous, which is why the score weights permissions rather than counting them.
• An unknown slug is reported, not guessed. A missing add-on answers HTTP 404 and is logged as "check the slug" instead of silently disappearing from the output.
• The Actor honours your Maximum cost per run and stops when the cap is reached.