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Discovery Awaits: Finding Open Access Research Articles

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— by Fanny Liu

Previously, we have covered the open access movement for several times, focusing on publishing research in open access, for example:

Apart from publishing, researchers and the public can enjoy the benefits brought by open access – as readers. In this post, a few useful tools to discover open access articles will be introduced.

Browser extensions

Various browser extensions have been developed to help researchers quickly discover open access articles and freely accessible (green open access) copies of those behind a paywall on the publisher’s website, such as EndNote Click, Google Scholar Button, Open Access Button, and Unpaywall Browser Extension.

Among them, Open Access Button and Unpaywall Browser Extension are two open-source tools allowing users to get open access copies of the articles with one click – and designed to be free and legal. Below is a brief introduction to the tools.

  Open Access Button Browser Extension Unpaywall
Website https://openaccessbutton.org/   https://unpaywall.org/products/extension
Data source
  • Aggregated repositories in the world, hybrid articles, open access journals, and those on authors personal pages, e.g., Unpaywall, OpenAIRE, and Europe PMC
  • Data from open indexes like PubMed Central, the DOAJ, Crossref, and DataCite.
  • Independently monitoring over 50,000 unique online content hosting locations, including Gold OA journals, Hybrid journals, institutional repositories, and disciplinary repositories
Service charge Free of charge Free of charge
Browser supported
Core function On the publisher’s website, click on the modest extension button to find open access copy (See Figure 1) On the publisher’s website, click the visible green tab to find open access copy (See Figure 2)
Special feature When an article is not freely available, users can ask the authors to share it by putting it into a repository. With OA Nerd Mode enabled, OA status is indicated by color:
  • gold
  • green
  • bronze
  • grey (closed)
Source code Available under MIT license at https://github.com/oaworks/plugin Available under MIT license at https://github.com/ourresearch/unpaywall-extension
Developed by OA.Works OurResearch

Table 1: Introduction to Open Access Button and Unpaywall Browser Extension

Figure 1: Screenshot of Google Chrome browser with Open Access Button installed
Figure 2: Screenshot of Google Chrome browser with Unpaywall Browser Extension installed

Discovery platforms

Libraries’ subscribed academic databases such as Scopus and Web of Science have integrated Unpaywall data, allowing users to find open access articles easily. Open indexes are also being developed, supported by open metadata. There are already some popular openly available tools for researchers and the public to find open access articles, such as The Directory of Open Access Journals (DOAJ) and OpenAlex.

The Directory of Open Access Journals (DOAJ)

The Directory of Open Access Journals, DOAJ, is a unique and extensive index of worldwide open access journals. To ensure quality content is openly available, it has developed a set of criteria on open access, transparency, and quality control. Only journals meeting the criteria would be indexed in DOAJ.

As of 23 April 2025, there are 11,015,938 indexed open access articles.

By clicking “Articles” and entering keywords, users can search for articles from open access journals.

Figure 3: Screenshot of DOAJ as of 23 April 2025

OpenAlex

OpenAlex is a comprehensive catalogue of research outputs, including but not limited to research articles, datasets, books, and dissertations. It also uses the Unpaywall dataset as one of the data sources to identify open access works. OpenAlex dataset is completely free under the CC0 license.

As of 23 April 2025, there are 266,329,537 works, among which 60,819,303 have an open access copy. As for articles, 44,466,735 open access articles have been indexed by OpenAlex.

Users can simply search for works with keywords and add a filter for “Open Access” (and work is open access) to discover research outputs which are open access.

Figure 4: Screenshot of OpenAlex as of 23 April 2025

Conclusion

This post introduces several tools to help researchers and the public discover open access articles, including browser extensions like Open Access Button, and Unpaywall, as well as discovery platforms like the Directory of Open Access Journals (DOAJ) and OpenAlex. These tools leverage extensive data sources, in order to facilitate free, quick, and legal discovery of research articles which have already been made open access.

Extended readings

References

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