Terms of use

Effective 9 November 2026

OpenArc Models is a free educational website run by Chi-Hua Chien in the United States (“we”). By using it, you agree to these terms. They’re written to be read, so please do. Questions? Contact: an email address will be listed here soon.

Learning, not professional advice

OpenArc Models’ models, lessons, quizzes and readouts are simplified teaching material. Models aren’t to scale unless stated, animations show ideas rather than exact behaviour, and readouts come from textbook equations, not validated simulations. Nothing here is engineering, medical, safety, legal or financial advice. Don’t rely on OpenArc Models to design, build, diagnose, treat or operate anything real. We work hard on accuracy, but mistakes are possible; if you spot one, please tell us.

Using OpenArc Models

You may use OpenArc Models for free to learn, teach and explore. Teachers may show it in class, link to any model and print the handouts for their students.

Please don’t try to break, overload or hack the site, copy it wholesale, or use it for anything unlawful.

Who owns what

The OpenArc Models name, website, 3D models, lessons and images are © 2026 Chi-Hua Chien. You may not republish or sell them, or use them to build another product, without permission. Linking to OpenArc Models, sharing screenshots for learning and embedding a model as described below are always fine. OpenArc Models is built with open-source software, listed with its licences in the licence notices; those parts stay under their own licences.

Your notes are yours. They stay in your browser; we never see them.

Embedding a model

You may show an OpenArc Models model on your own website for free, using the embed code we provide. An embedded model is still ours: it’s shown to you, not given to you, and you get no ownership of it or right to it beyond showing it this way.

You must keep it loading from OpenArc Models and leave it unchanged, with the OpenArc Models name and link visible. You may not hide, cover or remove them, download, copy or host the model files yourself, put a model in your own app or product, charge people to see it, present it as your own, or use it on a site that’s unlawful or misleading. We may change or stop embedding, or block a site from it, at any time.

Profiles and PINs

Profiles live in your browser on your device. A PIN only deters casual access on a shared computer, so keep it private and don’t reuse one from somewhere important. Clearing your browser’s data deletes your profiles and progress; save a backup from Settings if you want to keep them.

Other websites

Lessons link to outside references. We don’t control those sites and aren’t responsible for their content.

No guarantees

OpenArc Models is provided “as is” and “as available”, without warranties of any kind, to the fullest extent the law allows. We don’t promise it will always be available, error-free or suitable for a particular purpose, and we may change or remove features at any time.

Limits on liability

To the fullest extent the law allows, we aren’t liable for any indirect, incidental or consequential loss, or for any loss of data, that comes from using or being unable to use OpenArc Models. OpenArc Models is free, so our total liability to you for any claim is limited to US$0, or the smallest amount the law permits. Some places don’t allow these limits; where they don’t, they apply only as far as the law allows.

Changes

We may update these terms. When we do, we’ll change the effective date at the top. Continuing to use OpenArc Models after a change means you accept the updated terms.