Is Greasemonkey safe?

Clean risk

Greasemonkey automatically updates installed user scripts from remote URLs without hash or signature verification.

Every 3 hours to 7 days, Greasemonkey fetches updated code from each user script's declared @downloadURL and silently replaces the installed version if a newer one is found. No user confirmation is requested and no integrity check is performed on the downloaded code before installation. The updated script is then injected into matching web pages on the next navigation.

Anthony Lieuallenv4.14Firefox Add-ons
3Risk
Who publishes it

Anthony Lieuallen - no other listings under this identity

What this publisher told the store about itself, and the other listings that told it the same thing.

Publisher
Anthony Lieuallen

AI-generated. Findings may contain errors. Those marked Verified have been manually reviewed.

Publishers can request a review.

What it can do

Permissions this extension asks for, as declared in version 4.14. Asking for a permission is not a finding on its own - it is what the extension can do if it chooses to.

  • Read and change your data on every site you visit

    <all_urls>

  • Write to your clipboard

    clipboardWrite

  • Read and change cookies, including the ones that keep you signed in

    cookies

  • Start, monitor and manage your downloads

    downloads

  • Show you desktop notifications

    notifications

  • Store data in your browser

    storage

  • See the address and title of every tab you have open

    tabs

  • Store an unlimited amount of data in your browser

    unlimitedStorage

  • See every page you navigate to, as you navigate to it

    webNavigation

  • Watch every request your browser makes

    webRequest

  • Watch, block and rewrite every request your browser makes

    webRequestBlocking

Updated 2 November 2026amo-748