Last updated: May 2026. What we collect, why, who we share it with, and how to opt out.
subnetmaskcalc.net is a static site. All subnet calculations, the AI assistant, VLSM planner, and cheat sheet PDF generation happen entirely in your browser — we never see what you type into the calculators. To keep the site free, we use Google Analytics for traffic statistics and run banner ads through Google AdSense and Adsterra. These third parties may set cookies and collect data as described below. Visitors in the EU/EEA, UK, Switzerland, and California see a consent banner and can reject all advertising and analytics cookies. Everyone can withdraw consent at any time via the "Cookies" button in the lower-left corner.
The IPs, CIDRs, host counts, subnet plans, IaC parameters, and natural-language descriptions you enter never leave your browser. Calculations run in client-side JavaScript. There is no server-side endpoint receiving any of this data.
The Learn Center stores your lesson completion checkmarks, quiz streak, and theme preference (light/dark) in your browser's localStorage. This data lives only in your browser and is not synced anywhere. You can clear it at any time with your browser's "clear site data" function or the "Reset progress" button in the quiz.
Like most websites, our hosting provider records standard request logs (IP address, user-agent, requested URL, timestamp). These are kept briefly for security and abuse detection.
We use Google Analytics (measurement ID G-2BCVPV2NGL) to understand which pages are popular, which devices people use, and roughly where in the world our traffic comes from. We have enabled IP anonymization. Google Analytics sets the following cookies:
_ga — distinguishes users; 2-year expiration._ga_<container-id> — session state; 2-year expiration.You can opt out site-wide by installing the Google Analytics Opt-out Browser Add-on, or click "Reject all" on our consent banner. Google's privacy policy: policies.google.com/privacy.
We may serve display ads through Google AdSense. AdSense uses cookies and device identifiers to measure ad interactions and (where you have consented) to show personalized ads. Where consent is required, we use Google's Consent Mode v2 to signal your choice; if you reject ads, you may still see ads, but they will be non-personalized (contextual). To opt out of personalized advertising across the Google ad network, visit adssettings.google.com. To opt out of third-party vendor cookies industry-wide, see optout.aboutads.info (US) or youronlinechoices.eu (EU).
We also serve banner ads through Adsterra. Adsterra may set cookies and use device identifiers to deliver and measure ads. Visit Adsterra's privacy policy at adsterra.com/privacy-policy for details and opt-out options.
The site loads the Inter Tight, JetBrains Mono, and Instrument Serif fonts from Google's font CDN. The Learn page also loads jsPDF from cdnjs.cloudflare.com to generate the cheat sheet PDF in your browser. These providers may log requests for the assets they serve. We have no control over their logging.
The cookies set on this site fall into three categories:
localStorage for theme, lesson progress, quiz state, and your consent choice. Never sent to any server.Under the EU General Data Protection Regulation and the UK GDPR, you have the right to:
To exercise any of these rights, email contactus@subnetmaskcalc.net. Because we do not store user accounts, the most effective way to delete data we hold is to clear your browser's site data for subnetmaskcalc.net and to use the third-party opt-out links above for Google and Adsterra.
Under the California Consumer Privacy Act (as amended by the CPRA), California residents have the right to:
We honor Global Privacy Control signals as a valid opt-out request where applicable.
The site is suitable for use by anyone interested in learning networking. We do not knowingly collect personal information from children under 13 (US) or under 16 (EU). If you believe we have inadvertently collected such information, contact us and we will delete it.
We retain server access logs for up to 30 days. Google Analytics retains user-level and event-level data for 14 months (the minimum offered). Cookie expirations are listed in each vendor's section above.
Google and Adsterra are international service providers that may process data outside your country of residence, including in the United States. They rely on Standard Contractual Clauses and similar safeguards for EU-to-US transfers.
The contact page lists our email address — there is no contact form on the site, and we do not collect any form data. When you click the email link, your local email client opens with a new message addressed to us. The email goes directly to our team; no third party intercepts it.
If we change anything material — adding a new vendor, changing retention periods, expanding cookie use — we will update the "Last updated" date and (where required) notify EU/CA users via the consent banner.
Questions about privacy, data access, or deletion requests? Email contactus@subnetmaskcalc.net.