License & Usage

Free for teaching. Voluntary support welcome. Licensed for commercial use.

RealOChem is built to be used and shared. Students and instructors can use everything here for free. The only thing that needs a paid license is commercial use — for example, a textbook or other product, sold for profit, that embeds or depends on this material.

Content — free for teaching & study

The educational content of RealOChem (practice problems, explanations, hints, instructional text, and answer keys) is licensed under Creative Commons Attribution–NonCommercial 4.0 (CC BY-NC 4.0). In plain terms, you are free to use, copy, and adapt it, as long as you:

Give credit (BY) — cite “RealOChem” and link back to realochem.com.
Keep it non-commercial (NC) — no use for commercial advantage without a license (see below).

Classroom and individual study use is non-commercial and welcome at no cost. You do not need to ask permission or pay anything to use RealOChem with your students or for your own learning.

Institutional Supporter License

If RealOChem is useful in your course and you’d like your institution to support it, there is a named license your department, library, or course-materials budget can pay for — something a “tip” can’t easily be.

Suggested: $50 / year per institution.
Invoice on request — purchase-order friendly, so it can be reimbursed through normal channels. A one-time or perpetual arrangement is available if your institution prefers.
Honor-based. The site stays fully open — there is no paywall or lockout. This is a way to support the work, not a gate in front of it.

To request a license or an invoice, email realochem@gmail.com.

Commercial & textbook use

Using RealOChem content in a product offered for sale — a textbook, course pack, app, or other commercial offering that embeds or depends on it — falls outside the free license and requires a separate commercial license. I’m glad to work something out; please get in touch at realochem@gmail.com.

Just want to chip in?

Individuals and students who’d simply like to say thanks can use the tip jar. That’s a donation, not a license — the Institutional Supporter License above is the better fit if you need something an institution can reimburse.

The site’s source code is a separate matter from the content above (Creative Commons licenses aren’t meant for software). The code is © 2026 Dennis Cao, all rights reserved. The repository is public so the work can be read and learned from, but viewing it does not grant a license to reuse the code.

The RealOChem name

“RealOChem” and the RealOChem logo are reserved trademarks. No license above grants the right to use the name or brand — so nothing built on this material may present itself as RealOChem.