Sources
Sources are where works live: the journals, repositories, conference proceedings, ebook platforms, and book series that host scholarly output. OpenAlex tracks about 255,000 sources; roughly 80% are journals, with repositories, conferences, and book series making up most of the rest.
Sources and works: locations
A work connects to sources through its locations. Many works exist in more than one place — published in a journal, with another copy deposited in a repository. OpenAlex records all of these versions, and designates one location holding the work’s version of record as the primary location — typically the version accepted and published by a journal. See Versions for how versions are modeled, and the Works API reference for the location object itself.
Source types
Every source carries a type:
| Type | What it is |
|---|---|
journal |
Peer-reviewed serials — the large majority of sources |
repository |
OA repositories like arXiv or institutional repositories |
conference |
Conference proceedings series |
ebook platform |
Book-hosting platforms |
book series |
Serial book publications |
metadata |
Metadata-only sources |
other |
Everything else |
Curated source lists
OpenAlex deliberately does not impose a quality bar on which sources it indexes. Instead, it carries flags for membership in externally curated allow lists, so you can narrow to trusted sources when your analysis calls for it:
is_in_doaj— the source is indexed in the Directory of Open Access Journals, which vets the legitimacy of fully-OA journals. About 23,000 sources.is_core— the source is on the CWTS Core sources list (about 36,000 sources). See below.
CWTS Core sources
The Centre for Science and Technology Studies (CWTS) at Leiden University maintains the Core sources list: the subset of OpenAlex sources included in their Leiden Ranking Open Edition. Filtering works by primary_location.source.is_core returns only publications from those sources — letting you explore the data underlying the rankings, or negate the filter to see what the rankings exclude.
CWTS Core is not the same thing as the Web of Science Core Collection, a selective journal list maintained by Clarivate. The similar names are coincidence; the lists have different maintainers, criteria, and contents.
Related pages
- Journal quality & OA status — inclusion philosophy, fully-OA determination, and APC data
- Sources API reference — the Source object and its filters
- How do I find the OpenAlex Source ID?