Privacy Notice

This English text is provided for convenience. For German users, the German version at /de/privacy is the authoritative version.

Effective: 2026-04-26

This notice explains how CalcLibrary processes personal data. The website is currently a static calculator site. Calculations run in the browser. There are currently no user accounts, no comment features, and no server-side storage of calculator results.

Controller

Benjamin Kannel
Kalkhofstraße 9
70567 Stuttgart
Germany
Email: info@calclibrary.io

Hosting and technical logs

The website is hosted via Vercel. When you access the site, the hosting provider processes technically necessary connection and access data such as IP address, timestamp, requested resource, referrer, and browser or device information. This is necessary to deliver the site, defend against attacks, maintain stability, and investigate errors. The legal basis is Art. 6(1)(f) GDPR.

The exact retention period for technical logs depends on the hosting provider's operational settings and the specific security or incident context. We do not use these logs to build user profiles.

Local browser storage

The site uses local browser storage for functional purposes. At the moment this mainly covers theme mode, the preferred unit system, and your choice regarding optional analytics and performance features. This information stays on your device until you delete or change it in your browser.

Consent management

Product analytics with PostHog are only activated after your explicit choice. Your choice is stored locally in the browser so the site can respect it. You can change or withdraw that choice at any time through the "Privacy settings" link in the footer. The legal basis for optional analytics is Art. 6(1)(a) GDPR.

Anonymous performance measurement with Vercel Speed Insights is treated separately and runs without consent in order to keep the site stable and performant. Details follow in the next section; the legal basis is Art. 6(1)(f) GDPR.

Performance measurement (Vercel Speed Insights)

Vercel Speed Insights is active across the entire site. It collects only technical performance metrics (Core Web Vitals such as LCP, INP, CLS) in aggregated form. It does not set cookies, does not store unique identifiers, and according to the provider's published documentation is not designed to reconstruct a browsing session or identify an individual visitor across pages. Vercel acts as a processor for this data.

Product analytics (PostHog) — only with consent

If you consent, we use PostHog Cloud EU for product analytics. We collect exactly two intentionally instrumented events:

• calculator_viewed when a calculator page mounts,
• calculator_result_shown when the first valid result renders in that session,

each carrying the properties calculator_id, category, and locale. On non-calculator pages, standard pageviews ($pageview) are also recorded. PostHog automatically attaches technical default properties such as the referrer, an approximate country (derived from the IP, without persistent IP storage), the browser's preferred language, and the device category.

To distinguish returning visits from first visits, PostHog stores a long-lived identifier in localStorage and in a cookie on the calclibrary.io domain. We do not link user accounts, do not call identify(), and do not enable session replay, heatmaps, or surveys. Calculator form inputs are not transmitted to PostHog. The legal basis is Art. 6(1)(a) GDPR.

Cookies and similar technologies

This site only sets cookies where strictly functional or after your consent. The consent choice itself and functional preferences (theme, unit system) live solely in your browser's localStorage. A PostHog cookie is set additionally only after you have consented to product analytics; if you withdraw consent, client-side capture is stopped.

Recipients and service providers

At the moment we mainly use the following recipients or processors for site operation:

• Vercel Inc. for hosting and for anonymous performance measurement with Vercel Speed Insights.
• PostHog Inc. for optional product analytics via the EU cloud region (only after consent).

International transfers and safeguards

Depending on the provider, support operations, corporate structure, or administrative access may create links to countries outside the EEA. Where a transfer to a third country takes place, we rely on the safeguards required under data protection law, such as an adequacy decision or appropriate contractual safeguards offered by the provider.

Advertising and marketing

We do not currently actively use advertising or marketing tracking technologies. If we introduce advertising, remarketing, or comparable technologies later, they will only be activated after any required prior consent. This notice and the privacy settings will be updated before that happens.

Retention

Browser-stored preferences and the consent choice remain until you delete or overwrite them. PostHog retains event-level analytics data, in the current configuration, for the provider's default period of approximately one year, after which data is aggregated or deleted. Vercel Speed Insights only stores aggregated performance metrics.

Your rights

Under the GDPR you may in particular have rights of access, rectification, erasure, restriction of processing, data portability, and objection to processing based on legitimate interests. Any consent you provide can be withdrawn at any time with effect for the future.

Right to complain

You have the right to lodge a complaint with a data protection supervisory authority, in particular in the Member State of your habitual residence, place of work, or the place of the alleged infringement.

Changes to this notice

We update this privacy notice when the website, service providers, or legal requirements change. The version published on this page is the current version.