Last updated: 23 July 2026
TNC Sim ("the app") is an open-source, browser-based CNC simulator for Heidenhain TNC programming, available at tncsim.org and as an Android application. This policy explains how the app handles your data.
TNC Sim does not ask you for personal information. Your NC programs and the simulation itself stay in your browser or on your device.
We do not collect personal data. The app has no user accounts, no login, and does not ask for your name, email, or any identifying information.
Any CNC program you write or import stays on your own device (in your browser or the app). It is not uploaded to any server. If you export a program, the file is saved locally by you.
The app may store small amounts of data locally on your device (for example your theme preference or lesson progress) so the app works better on your next visit. This data never leaves your device and can be cleared at any time by clearing your browser or app data.
The website uses a service worker and the Android app includes its application files locally so the simulator works offline. These files are stored only on your device.
The app contains no advertising or cross-site marketing tracking. The website uses Umami Cloud for cookieless, anonymous usage statistics. These include page views, referrers, general browser, device and country information, plus fixed events for simulation runs and quality, explicit Refine use, first editor use, Tool Table use, and Learn lesson progress. We never include NC programs, filenames, tool values, free text, bug reports or user identifiers in analytics events.
The website is hosted on Cloudflare Workers, which may process standard server request logs (such as IP address and browser type) for security and reliability, as described in Cloudflare's own privacy policy. We do not use this data to identify individuals.
Sending a report is entirely your choice; nothing is sent automatically. If you use the in-app Report a problem button, the report includes your current NC program together with basic technical details (app version, browser type, screen size, which area of the app you were in, and any recent in-app error messages). A suggestion does not include your NC program — only the version and basic device/browser details.
When you send a report it is published as a public issue on our GitHub repository, so anything it contains — including the NC program in a bug report — becomes publicly visible. The dialog warns you about this before you send. Do not include confidential or company program data. To send a report without a GitHub account, the app uses Cloudflare Turnstile to check that the request is not automated; Cloudflare processes this check as described in Cloudflare's own privacy policy. GitHub then hosts the resulting issue.
The app does not knowingly collect personal data from anyone, including children.
If this policy changes, the updated version will be posted on this page with a new date.
Questions about this policy? Contact info@tncsim.org.