Your data stays in your browser.
DigitSum is designed to keep your information private. This policy explains what we collect, why, and what control you have.
Last updated: March 2026
1. Controller identity and scope
DigitSum is operated by Jan Křenek, a self-employed entrepreneur registered in the Czech Republic. This policy covers digitsum.com and its localized versions. We are the data controller for personal data processed through the website, such as contact messages, analytics events, cookie consent records, and server request metadata.
2. Calculator inputs
DigitSum does not require accounts or personal profiles. The values you enter into calculators are processed in your browser and are not intentionally sent to our servers. This local-first design is especially important for finance, tax, health, and personal-planning calculators.
3. Data we may process
We may process technical data such as IP address, browser, device type, language, referrer, requested URL, and approximate location derived from network metadata. If you email us, we process the email address, message content, and any details you choose to include.
4. Legal basis
We process strictly necessary technical data to operate and secure the site based on legitimate interests. Analytics, advertising storage, ad personalization, and similar non-essential cookies are based on consent where required. Legal or tax record-keeping may be processed when required by law.
5. Cookies and local storage
We use cookies and local storage for functional preferences such as language, currency, unit system, and consent choices. Analytics and advertising cookies are only used according to your consent settings and applicable law. You can change cookie preferences from the footer cookie settings link.
6. Google AdSense and advertising cookies
Third party vendors, including Google, use cookies to serve ads based on a user's prior visits to your website or other websites. Google's use of advertising cookies enables it and its partners to serve ads to your users based on their visit to your sites and/or other sites on the Internet. Users may opt out of personalized advertising by visiting Ads Settings at google.com/settings/ads. You can also learn how Google uses information from sites and apps at policies.google.com/technologies/partner-sites.
7. Google Analytics
When you consent, we use Google Analytics to understand aggregate site usage, such as pages visited, approximate country, device type, and browser. Google Analytics should not receive calculator input values. Analytics retention is configured for 14 months, and you can also use Google's browser opt-out add-on at tools.google.com/dlpage/gaoptout.
8. Third-party services
We use Cloudflare for hosting, security, and content delivery. Cloudflare may process connection metadata such as IP address and request headers. We use Google services for analytics, consent, and advertising where enabled. Fonts are served locally to avoid third-party font requests for typography.
9. International transfers
Some providers may process data outside the European Economic Area. Where required, transfers rely on safeguards such as adequacy decisions, the EU-US Data Privacy Framework, or standard contractual clauses used by the relevant provider.
10. Data retention
Local storage preferences remain in your browser until you clear them. Google Analytics data is retained for 14 months according to our configuration. Contact messages may be kept as long as reasonably needed to answer the request, maintain a correction history, or protect the site from abuse.
11. Your rights
Under GDPR and similar laws, you may request access, correction, deletion, restriction, portability, or objection to processing where applicable. You may withdraw consent at any time through cookie settings. You also have the right to lodge a complaint with the Czech Office for Personal Data Protection (ÚOOÚ), Pplk. Sochora 27, 170 00 Praha 7, uoou.gov.cz.
12. Children
DigitSum is a general-purpose calculator site and is not directed to children. We do not knowingly collect personal information from children under 16.
13. California privacy notice
DigitSum is not designed to sell personal information. Advertising partners may process identifiers for personalized advertising where permitted by law and consent. Users can use Google ad settings, browser controls, and consent controls on this site to manage personalization choices.
14. Security
We use HTTPS, Cloudflare security controls, limited access to accounts, and reasonable technical and organizational measures to protect the site and related data. No internet service can guarantee absolute security.
15. Changes to this policy
We may update this privacy policy from time to time. Changes will be reflected on this page with an updated date. Material changes may also be highlighted in the site interface.
16. Contact
For privacy questions, consent questions, or data-rights requests, contact us through the Contact page or by emailing the address shown in the site footer.