Privacy Policy
Last updated April 27, 2026
In short
Calcly does not require an account, does not run server-side analytics on user behavior, and does not sell or share user-level data. Every calculator runs in your browser. The data you type stays on your device unless you share a link or print/PDF the result.
What we store on your device
- Theme preference (
localStorage:theme) — light or dark. - Display currency (
localStorage:calcly:currency). - Favorites (
localStorage:calcly.favorites) — a list of slugs you starred. - Recent (
localStorage:calcly.recent) — the last calculators you opened. - Saved scenarios (
localStorage:calcly.scenarios) — named snapshots of calculator inputs. - URL state — your current calculator inputs are reflected into the address bar so a copy/paste is a working share link.
Clearing site data in your browser deletes all of the above. None of it leaves your device.
Server-side requests
Calcly is a static-rendered Next.js application. Pages are served as pre-built HTML and JavaScript. Two server endpoints exist:
/api/fx— returns currency exchange rates. Cached at the edge for 6 hours; no per-user data attached./api/explain— optional plain-English explanation of a calculator's result. The prompt and result you submit are forwarded to Anthropic's API to generate text. No personally identifying information is included unless you typed some into the calculator. Subject to a per-IP rate limit.
Cookies
Calcly does not set tracking cookies. The geo-aware income-tax landing page may set a single non-tracking cookie (tax-country) when you explicitly pick a country, so we remember your choice on the next visit.
Third-party services
- Frankfurter (ECB) — Calcly fetches reference exchange rates from the European Central Bank's public dataset via Frankfurter. Calcly's server makes the request, not your browser.
- Anthropic — only when you click an explain button on a calculator and the operator has configured an API key.
Your rights
Because Calcly does not collect personal data, there is generally nothing for us to delete on your behalf. You can clear all Calcly-related data by clearing your browser's site storage for this domain.
Contact
Questions about this policy? Contact us.