If you typed "where to" into a search box, the shortest honest answer is OpenStax for full courses and Project Gutenberg for classics. Both are free, legal, need no account, and no card, and both work from any country with an internet connection.
Open Textbook Projects
OpenStax
OpenStax is a nonprofit education initiative that publishes college-level textbooks. Every book on the site is peer-reviewed, openly licensed, and available to read online or download as a PDF. The material is free because it is openly licensed, not because of ads or library deals. You do not need an account, a card, or a login. The books cover standard subjects like algebra, biology, economics, and physics, and they are current enough for most introductory courses. If you are a student who needs a textbook for a class next week, this is the first place to look.
Open Textbook Library
The Open Textbook Library is a directory of open textbooks. Every book listed there must be openly licensed, which means you can use, distribute, adapt, and change it with attribution. The library does not accept every license, it takes GNU and Creative Commons licenses except the No-Derivatives kind. You can download, edit, and redistribute any book on the site at no cost. No account, no card, no registration. The catalog is broad, covering everything from nursing to computer science. The books are not all equally current, so check the publication date on each title before you rely on it for a fast-moving field.
Project Gutenberg
Project Gutenberg is a free public-domain ebook archive with over 70,000 ebooks. The books are free because their copyright has expired or they are otherwise in the public domain. That means you get the original text, not a modernized edition. No account, no card, no country restrictions. This is the place for classic literature, philosophy, history, and older scientific works. It is not the place for a 2024 organic chemistry textbook, those are still under copyright. But if you need Plato, Darwin, or Jane Austen, this is the fastest download on the internet.
Internet Archive’s Texts Collection
The Internet Archive hosts a huge collection of digital texts. Some are public-domain books; others are works contributed directly by authors or rights holders. You can read online or download. No account is required for most downloads, and no card is ever needed. The collection includes textbooks, old manuals, and out-of-print academic works. The catch is that some books are borrow-only, meaning you can read them for a limited time, like a library. But the free full-text items are genuinely free. This is a good second stop if OpenStax or the Open Textbook Library do not have what you need.
Google Books
Google Books can give you full text for many public-domain books. The service is a discovery and reading tool, not a textbook-only source. The free material is free because those books are in the public domain. No account, no card, no country limits. You can search inside a book for a term and read the matching pages. For out-of-copyright academic texts, this is useful. For current textbooks, it will only show you previews. Use it as a supplement, not a primary source.
HathiTrust Digital Library
HathiTrust offers public-domain titles for full-text reading. Copyright-protected works are only searchable by keywords, you cannot read the full text of those. So the free full text is limited to public-domain material. No account, no card, no country limits. This is a scholarly archive, so the interface is not flashy. But if you need a scanned copy of a 19th-century scientific paper or an old government report, this is a reliable place. It is not for current textbooks.
The Palace Bookshelf
The Palace Bookshelf, part of the Digital Public Library of America, has more than 11,000 free ebooks, including classics and some textbooks. It does not require an account or registration. The free status comes from being a library collection of free-to-download books. No card, no country limits. This is a good option if you want a clean mobile reading experience. The selection overlaps with Project Gutenberg, but the interface is different. Try it if you like browsing covers rather than searching by title.
University Presses
University presses are the traditional publishers of academic monographs and textbooks. Most of them charge money. There is one notable exception from the past: Oxford University Press made over 200 digital textbooks free online during the COVID-19 period, but that access was temporary and ended on September 30, 2020. That offer is gone. Do not go looking for it. As of now, no major university press offers a permanent, free, current textbook catalog. If you find a university press site that asks for a login or a card, that is normal, they are commercial publishers. Do not waste time trying to find a free official university-press textbook that does not exist. Use the open projects above instead.
What People Get Wrong
The biggest mistake is assuming that "free textbook" means "old edition" or "low quality." That is false for OpenStax and the Open Textbook Library. Those books are peer-reviewed and openly licensed, which means they are written and checked like commercial textbooks, but distributed without the price tag. The second mistake is assuming that every free ebook site is legal. That is not true. Stick to the sites listed here, they are all legal, and none of them will ask for a card or an account.
The third mistake is ignoring the publication date. Public-domain books are old by definition. Open textbooks vary. A book on calculus from 2015 is fine. A book on data science from 2015 is outdated. Check the copyright page or the "about" page on each book before you rely on it. That takes thirty seconds and saves you from studying wrong material.
What to Check Before You Commit
Before you download a textbook, check three things. First, the license. OpenStax and the Open Textbook Library use open licenses, but not all open licenses are the same. If the license says "No Derivatives," you cannot modify the book. If it says "Non-Commercial," you cannot sell it. For personal study, none of that matters. But if you are a teacher who wants to adapt the book for your class, check the license first.
Second, the edition. Older editions are often free or cheap, but they may not match the required readings for your course. If your professor says "4th edition," a free 2nd edition will not work. Compare the table of contents before you commit.
Third, the file format. Most open textbooks offer PDF. Some offer EPUB or MOBI for e-readers. If you need a specific format, check before you download. A PDF works on any device, but it does not reflow on a phone screen. EPUB is better for phones but less common on textbook sites.
Frequently Asked Questions
Are these books really free, or is there a catch?
They are really free. OpenStax and the Open Textbook Library use open licenses that allow free use and distribution. Project Gutenberg and the Internet Archive host public-domain works. No one is selling your data, and there are no hidden fees. The only cost is your time to download the file.
Can I print these textbooks or use them on a tablet?
Yes. Openly licensed books can be printed, and most sites offer PDFs that work on tablets. For a tablet, download the PDF and use a reader app. For printing, check the license, some open licenses allow printing, and none of the ones on these sites forbid it for personal use.
How current are the textbooks on these sites?
OpenStax updates its books regularly, and each book has a publication date on its page. The Open Textbook Library also lists dates. Public-domain books are old by definition. If you need the latest research in a fast-moving field, use a library database instead. For standard introductory courses, the open textbooks are current enough.
Do I need to create an account to download anything?
No. None of the sites listed here require an account, a registration, or a card for downloading public-domain or openly licensed books. The Palace Bookshelf explicitly states it requires no account. Project Gutenberg and the Internet Archive let you download directly. If a site asks for a card, it is not one of these sites.
What if I cannot find my textbook on any of these sites?
Then check your school library. Many libraries have digital textbook programs. Also check the Internet Archive’s lending library, which has some current textbooks available for borrowing. If that fails, ask your professor if an older edition would work, it often will, and older editions are sometimes free or very cheap.
More on ebooks
This is one of the guides in Where to Download Free Ebooks Legally. The others:
