Is CORE Econ really free to use?

Yes. CORE Econ describes its ebooks as "free, open access" texts, and its homepage states the project offers "free online textbooks and resources" that are "free to everyone." The site does contain a Stripe payment integration and a "Support CORE" section, but those are donation and support channels, not paywalls. You can read the ebooks without paying.

What "free" covers

The homepage lists the full ebook library as open access, including:

• The Economy 2.0: Microeconomics — described as a "free, open access text" for introductory undergraduate microeconomics
• The Economy 2.0: Macroeconomics — the same for introductory macroeconomics
• Understanding our Economy — a free textbook for beginners and first-year students
• The Economy 1.0 — the original free, open access text for a year-long introductory course
• Doing Economics, Experiencing Economics, CORE Insights, and Economy, Society, and Public Policy
• Multiple translations (Spanish, French, Italian, Finnish, Portuguese, German, Slovak) and adaptations such as The Economy: A South Asian Perspective, all labelled free or open access

So the core teaching material — the ebooks themselves — sits behind no payment step.

What the Stripe link and "Support CORE" section actually are

The page includes a "CORE needs your help" heading and a "Support CORE: Non-US residents" link, and Stripe appears as a payment platform. These are voluntary giving routes for people who want to fund the project. Nothing in the page evidence ties them to accessing an ebook. Paying is optional; reading is not conditional on it.

Registration and extra resources

The homepage says: "Register below to access additional instructor and learner resources." That tells you two things:

1. Some additional resources (aimed at instructors and learners) require an account.
2. The ebooks are presented separately from that registration prompt, as the open-access library.

Registration is not described as paid. The page does not state a price for registered resources, so treat "free to register" as unconfirmed rather than assumed — but there is no evidence of a fee either.

Quick check before you commit

Bottom line

If your concern is cost, CORE Econ's textbooks are free to read and use. The only money-related elements on the homepage are voluntary support options. If you later want instructor or learner extras, you may need to register — check that step directly, since the page does not spell out its terms.