# Unpaywall [Unpaywall](https://unpaywall.org) is an open database with over 20 million free scholarly articles harvested from over 50,000 journals and open-access repositories around the globe. Sources for these articles include repositories run by renowned universities, governments, and scholarly societies. Unpaywall is integrated into thousands of existing search engines, library platforms, and information products, making articles easy to find, track, and use for your scholarly communication needs. The Unpaywall database has a very simple structure: it has one record for each article with a Crossref DOI. It harvests from many sources to find Open Access content, and then matches this content to these DOIs using content fingerprints. So for any given DOI, we know about any OA versions that exist anywhere. To fetch entries from Unpaywall indirectly through Crossref, choose **Search → Web search**, and the search interface will appear in the side pane. Select **Crossref** in the dropdown menu. To start a search, enter the words of your query, and press Enter or the **Fetch** button. The results are displayed in the [import inspection window](https://docs.jabref.org/v4/import-export/import/importinspectiondialog). In case an error occurs, it is shown in a popup. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.jabref.org/v4/finding-sorting-and-cleaning-entries/import-using-online-bibliographic-database/unpaywall.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.