Legal

Privacy Policy

How we collect, use, and protect your information.

Last updated: May 26, 2026  ·  Effective: May 26, 2026
This Privacy Policy explains how cidrcalculator.net ("we," "us," or "our") collects, uses, and shares information when you use our website at https://cidrcalculator.net (the "Service").

1. Information we collect

1.1 Information you provide

We collect information you voluntarily provide, including:

  • Contact form submissions — name, email address, and message content when you contact us

1.2 Information collected automatically

When you use the Service, we automatically collect:

  • Usage data — pages visited, features used, time on page, referring website
  • Device information — browser type, operating system, screen size, language
  • IP address — used for analytics aggregation and abuse prevention; not linked to individual identity by us
  • Cookies and similar technologies — see Section 4

1.3 Calculation inputs (NOT collected)

CIDR ranges, IP addresses, subnet designs, and similar inputs you enter into our calculators are processed entirely in your browser and are NOT transmitted to our servers or stored by us, unless you explicitly choose to save them to a logged-in account. We have no way to see what specific networks you calculate.

2. How we use information

We use collected information to:

  • Provide, maintain, and improve the Service
  • Respond to your inquiries and support requests
  • Analyze usage patterns to improve features
  • Display advertising relevant to your interests
  • Detect and prevent fraud, abuse, and security issues
  • Comply with legal obligations

3. Third-party services we use

3.1 Google Analytics

We use Google Analytics, a web analytics service provided by Google LLC ("Google"), to understand how visitors use our site. Google Analytics uses cookies and similar technologies to collect anonymized data about your visit, including pages viewed, time spent, traffic sources, and device characteristics.

This data is processed in aggregate form. Google may use this data to provide its own services. You can opt out of Google Analytics tracking by installing the Google Analytics Opt-out Browser Add-on.

More information: Google's Privacy Policy · How Google uses data

3.2 Google AdSense

We use Google AdSense to display advertising on our Service. Google AdSense uses cookies, web beacons, and other technologies to:

  • Serve advertisements based on your prior visits to our site and other sites on the internet
  • Personalize ads based on inferred interests and demographics
  • Measure ad performance and prevent fraud

Third-party vendors, including Google, use cookies to serve ads based on a user's prior visits to our website or other websites. Google's use of advertising cookies enables it and its partners to serve ads to our users based on their visit to our site and/or other sites on the internet.

You may opt out of personalized advertising by visiting Google Ads Settings or aboutads.info/choices.

More information: How Google uses information from partner sites

3.3 Adsterra

We also display advertising via Adsterra, an advertising network. Adsterra and its partners may use cookies, pixel tags, and other tracking technologies to:

  • Display targeted advertisements based on your activity
  • Measure the effectiveness of advertising
  • Detect non-human traffic and fraud

Adsterra collects technical information such as IP address, browser type, operating system, and referring URLs. For more information, please review the Adsterra Privacy Policy. You can opt out of interest-based advertising via the Network Advertising Initiative (NAI) opt-out or the European Interactive Digital Advertising Alliance (EDAA).

3.4 Other third-party services

We may also use:

  • Cloudflare — for content delivery and DDoS protection
  • Hosting providers — may collect server logs for operational purposes

4. Cookies and tracking technologies

We use the following categories of cookies:

4.1 Essential cookies

Required for the Service to function. Includes the theme preference (light/dark) and (if you sign in) authentication tokens. These cannot be disabled.

4.2 Analytics cookies

Used by Google Analytics to understand site usage. These can be disabled via your browser settings or the Google Analytics opt-out.

4.3 Advertising cookies

Set by Google AdSense, Adsterra, and their partners to display personalized advertising. These can be controlled via the opt-out links in Section 3.

4.4 Consent management

We implement Google Consent Mode v2 and a region-aware consent banner:

  • Users in the EU/EEA, the United Kingdom, and California (detected by browser timezone) see a consent banner on their first visit. Until they accept, all non-essential tracking — Google Analytics measurement cookies, Google AdSense personalization, and Adsterra advertising — is blocked. Even when consent is denied, Google may receive anonymous, cookieless pings used solely to count visits without identifying users.
  • Users elsewhere are auto-opted-in to analytics and advertising consistent with the laws of their jurisdiction. If you do not want analytics or advertising regardless of your location, you can request opt-out by contacting us, or block these services in your browser.

Region detection caveat: Timezone is an imperfect proxy. If you are travelling, using a VPN, or your device is misconfigured, your region may be detected incorrectly. To explicitly request a consent banner regardless of detected region, contact us via the contact page — we will honor manual opt-out requests from any user.

Consent expiration: Your consent choice is stored locally in your browser for 12 months. After that, the banner reappears so you can re-confirm. To change your choice sooner, clear your browser's site data for cidrcalculator.net and reload the page.

You can manage or block cookies through your browser settings. Note that disabling cookies may affect your experience.

4a. Your rights under GDPR (EU/EEA/UK) and CCPA/CPRA (California)

If you are located in the European Economic Area, the United Kingdom, or California (or any other US state with applicable privacy law), you have the following rights:

  • Access: request a copy of personal data we hold about you
  • Rectification: request correction of inaccurate data
  • Erasure: request deletion of your data ("right to be forgotten")
  • Restriction: request that we limit how we use your data
  • Objection: object to processing for legitimate interests, direct marketing, or profiling
  • Portability: receive your data in a portable, machine-readable format
  • Withdraw consent: at any time, with no effect on prior lawful processing
  • Do Not Sell or Share (California): opt out of any sharing of personal information for cross-context behavioral advertising

To exercise any of these rights, contact us via the contact page. We will respond within the legally required timeframe (one month for GDPR; 45 days for CCPA).

5. How we share information

We do not sell personal information. We share information only:

  • With third-party service providers as described in Section 3 (Google, Adsterra, hosting providers)
  • To comply with law, valid legal process, or government requests
  • To investigate or prevent fraud, security threats, or violations of our Terms
  • In connection with a business transaction (merger, acquisition, sale of assets)
  • With your explicit consent

6. Your rights

6.1 GDPR rights (European Economic Area)

If you are in the EEA, you have the right to:

  • Access — request a copy of the personal data we hold about you
  • Rectification — request correction of inaccurate data
  • Erasure — request deletion of your data ("right to be forgotten")
  • Restriction — request that we limit processing of your data
  • Portability — receive your data in a structured, machine-readable format
  • Object — object to processing based on legitimate interests, including profiling
  • Withdraw consent — for any processing based on consent
  • Lodge a complaint — with your local data protection authority

6.2 CCPA rights (California)

If you are a California resident, you have the right to:

  • Know what personal information we collect, use, and disclose
  • Request deletion of personal information
  • Opt out of the "sale" of personal information (we do not sell)
  • Non-discrimination for exercising your rights

6.3 Exercising your rights

To exercise any of these rights, email contactus@cidrcalculator.net with the subject line "Privacy Request." We will respond within 30 days.

7. Data retention

We retain personal information only as long as necessary for the purposes outlined in this Policy:

  • Contact form messages: 2 years
  • Newsletter subscriptions: until you unsubscribe
  • Account data: until you delete your account
  • Analytics data: as configured in Google Analytics (default 14 months)
  • Server logs: 90 days

8. Data security

We implement reasonable technical and organizational measures to protect your information:

  • HTTPS encryption for all data in transit
  • Encrypted storage for sensitive data at rest
  • Access controls and authentication for staff with database access
  • Regular security reviews

However, no internet transmission or storage is 100% secure. We cannot guarantee absolute security. See our Security page for more detail.

9. Children's privacy

The Service is not directed to children under 13 (or 16 in some jurisdictions). We do not knowingly collect personal information from children. If you believe we have collected information from a child, please contact us so we can delete it.

10. International data transfers

The Service is hosted on servers that may be located in the United States, Europe, or other jurisdictions. By using the Service, you consent to the transfer of your information to these locations. We rely on Standard Contractual Clauses and similar mechanisms for cross-border transfers as required by applicable law.

11. Do Not Track

Some browsers offer a "Do Not Track" signal. Because no industry standard for honoring DNT signals has been adopted, we do not currently respond to DNT signals. You can control tracking via the third-party opt-outs and cookie controls described above.

12. Changes to this policy

We may update this Privacy Policy from time to time. Material changes will be posted on this page with a new "Last updated" date. We encourage you to review periodically.

13. Contact us

For questions about this Privacy Policy or our data practices, contact:

cidrcalculator.net
Email: contactus@cidrcalculator.net
Subject: "Privacy Inquiry"