Privacy policy

This page explains what data Calclens collects, why, how long we keep it, and what your rights are under UK GDPR. Plain English, no hidden clauses.

This policy applies to calclens.com and any subdomains we operate (such as api.calclens.com). It does not apply to third-party websites we link to.

Who runs Calclens

Calclens is operated by an independent UK developer as a personal project. For the purposes of UK GDPR, the data controller is the operator of Calclens, reachable at [email protected]. We will publish a full business address here when one is registered for the project.

Short version

  • We don’t ask you to sign up, and we don’t keep accounts for you.
  • The numbers you type into a calculator stay in your browser unless you tap “Explain with AI”, in which case they’re sent (without identifiers) to our server and to Anthropic.
  • We use Google Analytics 4 to count visitors. We’re working to add a cookies banner so you can opt out before it loads.
  • We never sell your data. We don’t have it to sell.

What we collect

1. Information you actively give us

The only personal information you can give us is your email address, and only if you choose to enter it in:

We use this address only to reply to you (contact form) or to send you the launch announcement you signed up for (newsletter). We do not pass it to advertisers or any third party for marketing purposes.

2. Calculator inputs (when you use AI explain)

Your calculations run in your browser. The numbers you type do not leave your device unless you tap “Explain with AI”. When you do, the following is sent to our edge server at api.calclens.com and then to Anthropic’s Claude API:

  • The calculator identifier (for example, mortgage-uk)
  • The numbers you entered into that calculator
  • Your IP address (used only to enforce the daily request limit; not stored beyond 24 hours)

We do not attach your name, email, browser fingerprint, or any other identifier to these requests. Anthropic processes the request under their privacy policy; they are an EU- and US-based AI provider acting as our data processor.

3. Analytics data

We use Google Analytics 4 via the Site Kit plugin for WordPress. GA4 collects, in anonymised form:

  • Pages you visit on Calclens
  • How you arrived (search engine, direct, referral)
  • Approximate country and city (derived from a truncated IP)
  • Browser type, operating system, device category (mobile/desktop)
  • Time spent on pages, scroll depth

GA4 with default Google settings already truncates IP addresses before logging them, so we never see your full IP. We do not use GA4’s advertising features, audience-sharing, or Google Signals.

Cookies banner — work in progress. UK PECR rules require us to ask for your consent before loading non-essential cookies (including GA4). A consent banner is on our short-term to-do list and will appear on the site shortly. Until then, you can opt out of GA4 entirely using the official Google Analytics Opt-out browser add-on.

Cookies and similar technologies

Cookies are small text files stored by your browser. We use the following:

CookiePurposeLifespan
_gaGoogle Analytics — distinguishes unique visitors2 years
_ga_*Google Analytics — session state2 years
wordpress_*WordPress essential session (only set if you log in to the admin area — not relevant for visitors)Session

We do not use marketing or advertising cookies. We do not allow third-party trackers (Facebook pixel, ad networks, retargeting tools) on the site.

How long we keep your data

  • Email addresses (newsletter): until you unsubscribe, or until we close the newsletter
  • Contact form submissions: up to 12 months after the conversation ends, then deleted
  • Calculator inputs sent to AI: cached for up to 7 days (anonymised, keyed by a hash of the inputs); used to speed up popular calculations
  • IP addresses for rate-limit counting: 24 hours, then deleted
  • Google Analytics data: 14 months (GA4 default retention setting)

Legal basis (UK GDPR Article 6)

We process data under the following legal bases:

  • Consent (Article 6(1)(a)) — for the newsletter and, once the banner is live, for analytics cookies
  • Legitimate interests (Article 6(1)(f)) — for replying to messages you send us, and for rate-limiting AI requests to prevent misuse
  • Contractual necessity (Article 6(1)(b)) — for the future paid PDF reports feature, where applicable

Who we share data with

We use a small number of service providers (“data processors”) to run the site. Each is bound by contract to handle data only on our instructions:

We do not sell or rent personal data to anyone. We do not share data with advertisers.

International transfers

Anthropic and Google are US-based. Personal data sent to them is transferred under the UK International Data Transfer Addendum to the EU Standard Contractual Clauses, which is the UK government’s approved safeguard for such transfers.

Your rights under UK GDPR

You have the right to:

  • Access the personal data we hold about you
  • Rectify inaccurate data
  • Erase your data (“right to be forgotten”)
  • Restrict or object to processing
  • Withdraw consent at any time (for newsletter, or for cookies once the banner is live)
  • Data portability — receive your data in a structured, machine-readable format
  • Complain to the UK Information Commissioner’s Office at ico.org.uk

To exercise any of these rights, email [email protected]. We will respond within one month, usually much sooner.

Children

Calclens is a general-audience site, not directed at children under 13. We do not knowingly collect data from children. If you believe a child has sent us their email address through one of our forms, please email us and we will delete it.

Changes to this policy

If we change this policy materially, we will update the date at the bottom of this page and, if the change affects how we use existing personal data, notify newsletter subscribers by email.

Questions about your data?

Email [email protected] or use the contact page. We aim to reply within two working days.

Last updated: May 2026

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