Privacy Policy
Last updated: October 2026
Overview
Subnet.im is a client-side IPv4 subnet calculator and CIDR reference tool. All IP address calculations are performed entirely in your browser using JavaScript. No IP addresses, subnet data, or calculation results are ever transmitted to our servers. Your network information stays on your device.
Information We Collect
Information You Provide
None. Subnet.im does not require accounts, logins, or form submissions. There is no server-side storage of user input. IP addresses and CIDR prefixes entered into the calculator are processed entirely in your browser and are never sent to our servers.
Automatically Collected Information
We use a self-hosted instance of Plausible Analytics, a cookieless, privacy-focused analytics tool. It records page views and a small number of interactions (for example, using a copy button or the prefix length of a calculated subnet), along with referrer, browser, device type, and country. The addresses you enter are never included. Your IP address is used only to derive a daily-rotating anonymous visitor identifier and is not stored. No personally identifiable information is collected through our analytics.
Cookies & Local Storage
Essential
Your theme preference (light or dark mode) is stored in your browser's localStorage. This is not a cookie and is never sent to any server. It simply remembers your display preference between visits.
Analytics
None. Our analytics do not use cookies, localStorage, or any other persistent identifier on your device.
Third-Party Services
Subnet.im uses the following third-party services:
Data Retention
Anonymous analytics data is retained for 12 months, after which it is automatically deleted. No personal data is stored on our servers. Vercel server logs (which may include IP addresses and user agents) are automatically purged within 30 days per Vercel's data retention policy.
Your Rights
Regardless of your location, you can take the following steps to control your data:
- Clear cookies and localStorage in your browser settings to remove all locally stored data
- Disable JavaScript entirely (the site will not function, but no data will be collected)
EU/UK users (GDPR): You have the right to access, rectify, erase, restrict processing, and object to processing of your personal data. Since we do not collect personal data through our own systems, these rights primarily apply to data collected by third-party services listed above. Contact those services directly to exercise your rights.
California residents (CCPA): You have the right to know what personal information is collected and to request its deletion. As noted above, Subnet.im does not collect personal information directly. For data held by third-party services, contact those services using the privacy policy links in the table above.
Children's Privacy
Subnet.im is not directed at children under the age of 13. We do not knowingly collect personal data from children. If you believe a child has provided personal information through a third-party service on our site, please contact us so we can take appropriate action.
International Users
Subnet.im is hosted on Vercel's global CDN, which serves content from edge locations worldwide. Usage analytics are processed by our own self-hosted Plausible instance. Because we do not collect personal data through our own systems, there are no personal data transfers to be concerned about. Third-party services operate under their own data processing agreements and privacy policies.
Changes to This Policy
We may update this privacy policy from time to time. The “Last updated” date at the top of this page will be revised when changes are made. Material changes will be noted in this section. We encourage you to review this policy periodically to stay informed about how we protect your privacy.
Contact
For privacy-related concerns or questions about this policy, please open an issue on our GitHub repository.