How to Find Open Access PDFs and Convert Them to EPUB — Free Research Reading (2026)
Paywalled papers are only part of the academic literature. A large and growing proportion of research is freely available as open access PDFs — from preprint servers, publisher open access programs, government mandates, and institutional repositories. Here's how to find them and read them on your e-reader.
Major open access sources
arXiv (arxiv.org)
The largest preprint server in the world. Covers math, physics, CS, statistics, quantitative biology, economics, and electrical engineering. Every paper is freely downloadable as PDF. Just search on arxiv.org, open the paper, click "Download PDF," convert with pdf2epub.toolkit.bot, and read on your e-reader. See our arXiv to EPUB guide for details.
PubMed Central (PMC)
The US National Library of Medicine's free full-text archive. All NIH-funded research must be deposited here within 12 months. Over 8 million papers freely available. Search at pubmed.ncbi.nlm.nih.gov — papers with free full text show a "Free PMC article" link. See our PubMed to EPUB guide.
PLOS, eLife, Frontiers, PeerJ
Fully open access publishers — every paper is free. PLOS ONE, PLOS Biology, PLOS Medicine are high-volume, high-citation journals. eLife covers life sciences and biomedicine with rigorous peer review. Frontiers and PeerJ publish across many disciplines.
Unpaywall browser extension
Install Unpaywall (unpaywall.org) in Chrome or Firefox. It runs silently in the background and shows a green tab on any paper page when a free legal version exists. Covers arXiv, PMC, institutional repositories, and publisher open access pages. No effort required — it finds the free version automatically.
Google Scholar
Search Google Scholar (scholar.google.com) and look for PDF links on the right side of each result — these often link directly to free versions hosted by authors or repositories. See our Google Scholar to EPUB guide.
Open Access Button
Similar to Unpaywall, the Open Access Button (openaccessbutton.org) finds free legal versions of papers. Paste in a DOI, title, or URL and it searches repositories worldwide. Particularly useful for older papers not indexed by Unpaywall.
Publisher open access programs
| Publisher | Open access option | Coverage |
|---|---|---|
| Elsevier / ScienceDirect | Open Access articles (gold OA badge) | Growing subset, especially Horizon-funded |
| Springer Nature | Nature Communications, Scientific Reports fully OA; others hybrid | Large OA portfolio |
| Wiley | Wiley Open Access journals + hybrid articles | Growing |
| Taylor & Francis | Open Select + fully OA journals | Moderate |
| ACM | ACM Open — growing percentage | Increasing, esp. conference papers |
| IEEE | IEEE Open Access; many Xplore papers are OA | Moderate and growing |
Converting open access PDFs to EPUB
Once you have the PDF (from any open access source), the conversion workflow is the same:
- Go to pdf2epub.toolkit.bot
- Upload the PDF — conversion takes 30–60 seconds
- Download the EPUB and transfer to your e-reader
Frequently asked questions
What is open access and why does it matter for PDF conversion?
Open access means the paper is freely available to anyone without a subscription. This matters for conversion because you can legally download the PDF and convert it to EPUB for personal reading. Subscription-only papers require institutional access. Knowing the open access status tells you where to find a legal free copy.
Is arXiv all open access?
Yes. arXiv (arxiv.org) is a preprint server where authors self-publish versions of their papers freely. The papers on arXiv are the author's submitted or accepted versions — identical in content to the final published paper, just without the journal's typesetting. arXiv covers math, physics, computer science, quantitative biology, economics, and more. All arXiv papers are freely downloadable and convertible.
What is Unpaywall and how do I use it?
Unpaywall is a free browser extension (available for Chrome and Firefox) that automatically finds legal free versions of paywalled papers. When you're on a paper's abstract page at a subscription journal, Unpaywall checks over 50,000 open access repositories and shows a green tab if a free version exists. Click it to download the PDF directly. It's the fastest way to find open access versions of papers that appear paywalled.
Which publishers offer the most open access content?
PLOS (Public Library of Science) — all papers fully open access. eLife — fully open access, high-impact life sciences. PeerJ — fully open access across sciences. Frontiers — large open access publisher. Nature Portfolio — Nature Communications, Scientific Reports fully open access. Springer Open — many fully open access journals. BioMed Central — BMC journals fully open access. Many other traditional publishers have hybrid open access (some papers open, some subscription).
Can I convert papers from institutional repositories?
Yes. Institutional repositories (like Harvard's DASH, MIT OpenScholarship, or Stanford's SUL) host author manuscripts of papers that may be paywalled elsewhere. Search your institution's repository or Google Scholar for the author's uploaded version. These are legally free to download and convert. PubMed Central (PMC) is a government-funded repository with full text of NIH-funded papers — all freely downloadable.