Privacy notice (private beta).
Last updated 7 October 2026. This describes what the Keystone website and app actually do today.
Your structural models
Analysis and design run on your own computer, in the browser or in the Windows app. Models are kept in your browser's local storage (one autosave) and in files you save yourself. They are not uploaded to our server.
The AI assistant
When you use the assistant, the parts of your model, results and any files you attach that are needed to answer are sent through our server to OpenRouter, which forwards them to the AI model provider (currently OpenAI). Our server does not store the content of these requests; it records only metadata for rate limits and cost: time, your invite, the model used, token counts and cost.
You can turn the assistant off for any project (Assistant → Turn Off for This Project). The setting is saved with the model, and nothing from that project is sent anywhere.
Access request form
If you request access we store what you enter (name, work email, company, role, country, current software, team size, message), the time and your IP address, to reply to you and manage the beta. We do not sell this information or use it for advertising.
Sign-in
The app uses one cookie, set when you enter an invite code, to keep you signed in for up to 90 days. There are no analytics or tracking cookies, and the website loads no third-party scripts or fonts: everything is served from our own server.
Questions and deletion
Ask us to see or delete your access request or invite record by replying to your invite email, or through the access request form.