DOI lookup: from a DOI to the free PDF
Paste a DOI and get the paper it identifies, with a direct link to a free, legal copy when one exists. Bare DOIs, doi.org links, journal URLs and arXiv ids all work. No signup.
Try an example: 10.1038/s41586-021-03819-2
What a DOI lookup gives you
Every DOI names exactly one paper, so looking it up is the most reliable way to find an article. The paper page shows the title, authors, journal, year and abstract, the publisher's page, and every free copy the open-access indexes list, labelled by version: published article, accepted manuscript or preprint. If no free copy exists yet, it says so and offers the legal routes that remain.
How the lookup works
- The DOI is read out of whatever you paste, including links to publisher pages, Wiley, ScienceDirect, Springer and Nature article URLs, and doi.org links.
- The DOI registries, Crossref and DataCite, supply the paper's details. arXiv ids are turned into their DataCite DOIs.
- Unpaywall and OpenAlex report where free copies live: university repositories, PubMed Central, arXiv, bioRxiv, Zenodo and open-access journals.
Nothing is downloaded or stored here. Every link goes to the site where the free copy is legally hosted. The about page describes the data sources in more detail.
Where to find a paper's DOI
A DOI starts with "10." and is printed on the first page of most papers, in the citation on the publisher's page, and in reference lists. It is also the last part of a doi.org link. Our guide to what a DOI is and where to find it covers the details, and explains what to do when a paper has no DOI at all. If you only have the title, paste that instead: the finder searches the literature by title too.
Frequently asked questions
What does a DOI look up?
A DOI (digital object identifier) is a permanent id for a paper, such as 10.1038/s41586-021-03819-2. Looking it up returns the paper it names: its title, authors, journal and the publisher page. This tool also checks whether a free, legal copy exists.
Can I get a PDF from a DOI?
Often, yes. The DOI leads to the publisher, which may charge, but many papers also have a free accepted manuscript or preprint in a repository. Paste the DOI above and the tool lists every free copy the open-access indexes know about.
Does it work with a DOI link?
Yes. Paste the full link, such as https://doi.org/10.1000/xyz123, the bare DOI, a journal article URL containing the DOI, or an arXiv id. The tool extracts the DOI itself.
What if the DOI is not found?
Check for characters cut off at the end, such as a missing closing bracket, and remove any trailing full stop. Very new DOIs can take a day or two to appear in the registries. If the DOI is right, the paper page says so and offers legal routes to the paper.