Last updated: 15 October 2026
nuDefend Browser Guard is a free browser extension that warns you about known phishing and malware sites and stops you from visiting them. It is designed to keep your browsing private. This page explains exactly what information leaves your browser, when, and why.

At a glance
- We do not receive the addresses of the sites you visit or your browsing history.
- The extension has no ads or tracking. No information is sold or shared with third parties.
- No account is needed. The extension works without registration.

How site checks work
- The extension downloads a list of shortened identifiers for dangerous sites (SHA-256 hash prefixes). The list comes from our server (api.nuvpn.com) or our download server (downloads.nuvpn.com). It is the same for everyone and is updated several times a day.
- When you visit a site, the extension calculates an identifier from the site's name in your browser and checks it against the list. In the vast majority of cases, there is no match and nothing is sent.
- If a shortened identifier matches, the extension sends us only that identifier (8 characters). We return the full identifiers that start with it. The final comparison happens in your browser. The site's address and name are not sent.
- Important: the shortened identifier can reveal, at most, that you checked a site similar to one on the list.

What is sent to us
- Requests to download the list and check for updates. These requests are the same for everyone and contain no information about you.
- A shortened identifier, only when it matches an entry on the list, as described above.
- A report of an incorrectly blocked site is sent only if you click "Was this site blocked by mistake?" and confirm. The report includes only the site's name, not its full address. We keep it so we can review it, then delete it after 90 days. Our team receives the report by email and in a Telegram message. To review the report, we look up the site name in public databases, such as domain registration records, and in services that check website reputation. We send only the site name for these searches, with no information about you.
- As with any internet request, our servers, including the download server, see the IP address the request came from. We use this address only to limit the rate of requests and protect the service from abuse.

What is stored in your browser
The list, your settings, and the number of blocked sites are stored in your browser. Recent check results are also stored briefly. All of this stays in your browser and is deleted when you remove the extension. To let “Back to safety” return you to the previous page, the addresses of a few recently opened pages in each tab are also stored in the browser’s memory. These addresses are deleted when you close the tab.

Links to nuVPN
The extension includes a link to the website for nuVPN, our VPN service. The link includes tags (utm) that indicate you came from the extension. Our website receives this information only if you click the link. The extension itself does not send us any information about how you use it.

Permissions the extension requests and why
- Access to tab navigation (webNavigation): to check the site's name before the page opens.
- Request blocking (declarativeNetRequest): to block repeat visits to a site already identified as dangerous.
- Privacy settings (privacy): This permission is needed only if you turn on the setting that limits IP address exposure through WebRTC. The setting is off by default. When you turn it on, your browser will ask for your permission. When you turn it off, the extension gives up that permission.
- Storage and scheduling (storage, alarms): to save the list and settings and update the list periodically.
- Access to our servers only (api.nuvpn.com and downloads.nuvpn.com): The extension does not request access to the content of the sites you visit.

Children
The extension does not collect personal information, including personal information about children.

Changes to this policy
If we change what information is sent from your browser, we will update this page before the change takes effect. We will also note the change in the extension's release notes.

Contact
Privacy questions: privacy@nudefend.com. Support: support@nudefend.com.