Your data stays with you

Effective 9 November 2026

OpenArc Models has no sign-up, no ads and no tracking. Your progress is saved in your own browser, not on our servers. We count visits only as anonymous totals, which can’t tell visitors apart.

Who runs OpenArc Models

OpenArc Models is run by Chi-Hua Chien, in the United States (“we” on this page). Contact: an email address will be listed here soon.

What OpenArc Models saves, and where

To remember where you left off, OpenArc Models keeps these things in your browser’s own storage on your device:

• which models you’ve opened, your quiz and assignment scores, review schedule, puzzle times, challenges, missions and notes;
• models you’ve saved and your settings, such as the theme, text size and how deep you like lessons;
• copies of any models you choose to save for offline, which you can remove in Settings;
• device profiles, if you make them, including the display name you choose, so people sharing a computer can keep their progress apart.

None of this is sent to us, and we can’t see it. (The anonymous totals described below are counted separately and never include any of it.) It leaves your device only if you choose to save a backup file from Settings, and you decide where that file goes. To delete it, remove a profile in Settings or clear this site’s data in your browser.

A device profile can have a PIN. The PIN is stored scrambled (as a salted hash), not as the number itself. It stops someone casually opening your profile on a shared computer, but it isn’t strong security, so don’t reuse a PIN you use elsewhere.

What our web host sees

OpenArc Models is delivered by a hosting company, Cloudflare. When your browser asks for a page or a 3D model, Cloudflare handles technical details such as your IP address, browser type and the page requested, to deliver it and to protect the site from attacks. We don’t use this to identify you, and we don’t keep IP addresses. Cloudflare’s handling is described in its own privacy policy.

Anonymous statistics

To see which lessons help and what’s broken, OpenArc Models adds each visit to simple daily totals on our server, such as “the heart model was opened 40 times today” or “120 visits came from phones”. We count:

• visits, and whether the screen is phone-, tablet- or computer-sized;
• the country a visit comes from, worked out by Cloudflare from the connection and counted on its own (the address itself isn’t kept);
• the name of the website that linked to OpenArc Models, such as google.com, but not the page;
• which pages and models are opened, and how many tours, quizzes, challenges and other activities are finished, with quiz scores rounded to the nearest 10%;
• which features are used, and the names of errors the site runs into;
• for models embedded on other websites, how often each is shown and the name of the website showing it.

Each of these is a separate number added to a total for the day. We don’t use cookies or any id for this, and nothing is stored on your device for it, so the totals can’t be joined up, can’t tell one visitor from another and can’t follow anyone. They never include your name, profile, notes or answers.

To leave your visits out, turn off Include my visits in the totals in Settings. Nothing is counted if your browser sends “Do Not Track” or Global Privacy Control.

What we never do

• No advertising, and no selling or sharing of personal information.
• No cookies for visitors, no tracking across visits or websites, and no third-party scripts or analytics companies. Fonts, code and models all load from OpenArc Models itself.
• No access to your camera, microphone or location. “See it on your desk” hands the model to your phone’s own AR viewer, and OpenArc Models never receives the camera picture.

Optional things that involve someone else

• Reporting a mistake with the form. We receive what you type, which model it’s about and where you were in the lesson. Nothing else is sent: no name, no email address and nothing that tells us who you are. Before saving, we automatically remove anything that looks like an email address or phone number, but please don’t type personal details. We use reports only to fix lessons, and delete them when we’re done.
• Emailing us. If you choose to email us, or to report a mistake by email, we see your email address and what you wrote. We use it only to deal with your message. If you’re under 13, please ask an adult to send it with you.
• Read aloud. This uses your device’s or browser’s voice. OpenArc Models doesn’t send the text anywhere, but some browsers use an online voice service of their own.
• See it on your desk, on Android. This opens Google’s AR viewer, which fetches the model file from OpenArc Models and follows Google’s privacy policy. It only happens if you choose it.
• Models embedded on other websites. Those sites have their own privacy rules. The embedded model stores nothing on your device. It adds to the anonymous totals described above, including the name of the website showing it.
• Assignment links. The link holds the teacher’s title and chosen questions, not your name. Your code shows only your score, and you choose whether to share it.

Links to other websites

Lessons link to outside references, such as encyclopedias and textbooks. Those sites have their own privacy rules, which apply once you leave OpenArc Models.

Cloud accounts

OpenArc Models has no online accounts. If we ever add them, we’ll update this notice first, explaining what would be stored, who would store it and how to delete it. They would always be optional.

Younger visitors

OpenArc Models is for anyone curious about how things work. It doesn’t collect personal information from anyone, of any age, so you don’t need an account or a parent’s permission to use it. The anonymous totals can’t identify anyone. The only exception is an email you choose to send us, described above. If you have questions about privacy, ask a parent, guardian or teacher to read this page with you.

Your choices and rights

Apart from any email you send us, we hold no personal information about you; your browser data is fully in your control, as described above. To ask about or delete an email you sent, or for any other question or concern, contact us using the details above.

Changes

If this notice changes, we’ll update it here and change the effective date at the top.