gtcalc
Privacy Policy
Last updated 4 October 2026
gtcalc (gtcalc.app) is a free calculator for planning GregTech production lines. This page explains what we collect, why, who handles it for us, and what you can do about it. We don't show ads, we don't sell your data, and we don't track you across other sites.
What we collect
| What | When | Why |
|---|---|---|
| Email address, username, and a password or Google sign-in | Only if you create an account | To sign you in, keep your flows in sync, and let you reset your password. Passwords are handled by Firebase Authentication; we never see them. |
| Your name and email from Google | If you sign in with Google | To create your account. We only use the email; we don't post anything to your Google account. |
| Two-step sign-in details | If you turn it on | To protect your account. |
| Flows you save to your account | When you're signed in | So they're there on any device. |
| Flows you share to Community, with their name, description, schematic file and your username | When you press Share | To publish them. Shared flows are public: anyone can view, copy and download them. |
| Comments, votes, favourites and copies | When you use them | To show them on flows. Comments show your username. |
| Reports you send | When you report a flow or comment | So moderators can review it. Only moderators see reports. |
| Anonymous visit statistics: page, referring site, country, device and browser type, and page speed | Only if you press Accept on the cookie banner | To see how the site is used and how fast it loads (Vercel Web Analytics and Speed Insights). These use no cookies and can't identify you. |
| IP address and basic request details | On every visit | Our hosting provider keeps short-lived server logs for security and to keep the site running. |
What we store on your device
gtcalc keeps your canvas, saved flows and preferences (units, font, toolbar options, your cookie choice) in your browser's local storage, so the app works and remembers your work. If you sign in, Firebase keeps you signed in using your browser's storage. These are needed for the app to work, so they don't need your consent. They stay on your device until you clear your browser's site data.
We don't use advertising or tracking cookies. The analytics we use (only after you accept) are cookieless.
Who processes your data for us
- Google Firebase (Authentication and Firestore database): accounts, saved and shared flows, comments and votes. Database stored in London (europe-west2).
- Vercel: hosts the website, runs the link previews, and provides Web Analytics and Speed Insights.
- Google Fonts: the fonts load from Google's servers, so Google sees your IP address when the page loads.
- Cloudflare: runs the domain's DNS.
Some of these providers may process data outside the UK and EU. They do so under their standard data protection terms (such as the UK International Data Transfer Addendum and the EU Standard Contractual Clauses).
Moderation
To keep Community friendly, usernames, flow names, descriptions and comments are checked automatically for offensive words, and some go to a moderator for review. Moderators can remove content and rename usernames that break the Terms.
Legal bases
We use your account details and content to provide the service you signed up for (contract). We use logs and moderation to keep the service secure and fair (legitimate interests). We use analytics only with your consent, which you can withdraw at any time.
How long we keep it
- Account details and saved flows: until you delete your account.
- Shared flows and comments: until you or a moderator delete them, or your account is deleted.
- Analytics: only aggregated, anonymous counts are kept.
- Server logs: kept briefly by our hosting provider.
Your choices and rights
- Use gtcalc without an account: nothing personal leaves your browser except normal web requests.
- Change your cookie choice any time with Cookie settings at the bottom of the Guide.
- Delete flows you've shared from their page in Community.
- Under UK and EU data protection law you can ask for a copy of your data, ask us to correct or delete it, object to how we use it, or ask us to restrict it. To delete your account and everything linked to it, use Delete my account in the profile window.
- You can complain to the UK Information Commissioner's Office (ico.org.uk) or your local data protection authority.
Children
gtcalc isn't aimed at children under 13, and we don't knowingly collect their data. If you think a child has made an account, contact us and we'll remove it.
Changes
If we change this policy we'll update the date at the top. If a change affects how we use data you've already given us, we'll say so in the app.
Contact
Email privacy@gtcalc.app about anything on this page.