Sources Overview

Eg:S137773608Count:255,535Links:locations, publishers, indexes

A source is a venue where works appear: a journal, a conference proceedings series, a preprint or institutional repository, an ebook platform, or a book series. Sources are how OpenAlex connects works to the places that host them — every work links to one or more sources through its locations, and each source aggregates the works it published. OpenAlex tracks about 255,000 sources; a source’s OpenAlex ID looks like S137773608, and you can fetch one at api.openalex.org/sources/S137773608.

This page covers where sources come from and the judgment calls behind them. Repositories covers how repository content gets harvested and matched, and Attributes is the dictionary of every attribute on a source object.

About

Where sources come from

Sources are drawn from the works that flow into OpenAlex: as records arrive from Crossref, the Microsoft Academic Graph (MAG), DataCite, PubMed, repositories, and other feeds, the venues they name become sources. A source is identified primarily by its ISSN — OpenAlex groups every ISSN that shares an issn_l (linking ISSN) into a single source — with additional sources coming from repository and platform registries that have no ISSN. Each source is attached to the publisher that runs it via host_organization.

Source types

Every source carries exactly one type, assigned from its metadata and behavior. The vocabulary (see Source types):

Repository sources behave differently enough from journals — harvesting, matching, and why their work counts can look small — that they get their own page: Repositories.

No quality bar, by design

OpenAlex deliberately does not impose a quality bar on which sources it indexes — its inclusion criteria are more like arXiv than Web of Science. There are good reasons to index everything: “lower-quality” sources are useful as objects of study; sources that are inadequate for one purpose are ideal for another (grey literature, regional literature, early-career work); low-power studies aggregate into high-power meta-analyses; and excellent work is too often excluded from traditional indexes merely for being non-English or from the Global South. Most importantly, “lower-quality” content can always be filtered out if it’s included — it can’t be added back if it’s not.

Predatory journals are handled the same way. There is no authoritative list of them, the lists change constantly, and the definition itself is contested — from faked peer review (obviously problematic) to any publisher that inflates accepted volume for revenue (a practice common even at “reputable” sources). Rather than maintain a deny list and play cat-and-mouse with bad actors who can simply rebrand, OpenAlex indexes everything and lets analysts narrow down.

Allow lists

OpenAlex prefers allow lists (curated lists of trusted sources) over deny lists: they’re more transparent, easier to maintain, and a more robust foundation for retrieval. Two membership flags let you narrow to trusted sources:

• 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.

More filters like these are planned; the goal is a “quality vs. quantity” slider that users can adjust to their needs. Because the database is open, a list of sources to exclude is easy for one librarian to build and share; ask your local librarian if they’ve curated one.

CWTS Core vs. Web of Science

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:true returns only publications from those sources, letting you explore the data behind the rankings (or negate it to see what they exclude). CWTS Core is not the Web of Science Core Collection, Clarivate’s selective journal list — the similar names are coincidence, and the two have different maintainers, criteria, and contents.

Fully-OA journals and open access

Whether a journal is fully open access matters beyond the journal itself: it determines the OA status of the works inside it. An OA article in a fully-OA journal is gold; the same article in a toll-access journal is hybrid or bronze — so a work’s oa_status links back to the source’s openness recorded here. Two source fields carry the determination:

• is_in_doaj — the journal is indexed in DOAJ (about 23,000 sources). DOAJ verifies credibility and legitimacy; OpenAlex does no independent vetting, so use this field when legitimacy matters. If a journal is in DOAJ it is fully OA (is_oa=true, is_in_doaj=true).
• is_oa — the journal is fully OA, whether or not DOAJ lists it (about 65,000 sources).

Not every fully-OA journal is in DOAJ — smaller titles and journals from the developing world often aren’t. For those, OpenAlex applies two more checks: (1) is it from a known fully-OA publisher (a small allow list, e.g. many SciELO-model publishers)? and (2) does it publish only OA articles? Because OpenAlex indexes a journal’s complete output, it can simply observe whether every article is OA — a check that credits smaller publishers who never registered with DOAJ. A journal passing either check gets is_oa=true, is_in_doaj=false. This observation-based check also detects flipped journals (oa_flip_year): an OA article published before a journal’s flip date is hybrid or bronze, one published after is gold.

APC data

The article processing charge (APC) is the fee some journals charge to publish a work OA. At the source level OpenAlex records the journal’s list price in apc_prices (per currency) and apc_usd; at the work level it records both the list price and OpenAlex’s best estimate of what was actually paid. List prices are sourced from DOAJ plus manual curation. Two caveats: OpenAlex stores one (current-year) list price per journal, so historical estimates apply today’s price to an older year; and DOAJ coverage skews toward fully-OA journals, leaving hybrid journals — where much APC spending happens — thinly covered. For year-by-year list prices, Butler et al. 2024 (Harvard Dataverse, CC0) provides publisher price lists per journal per year (2019–2023, six large publishers, ~8,711 journals); OpenAlex is evaluating integrating this dataset but has not yet done so. For a worked example of estimating an institution’s APC spend, see Analyzing your institution.

Attributes

The full dictionary of every attribute on a source object lives on its own page: Attributes.

In the API

The Sources endpoint is at api.openalex.org/sources. Fetch a single source by ID — /sources/S137773608 — or a list, and filter, search, sort, and group over the source attributes (for example filter=is_in_doaj:true,type:journal or group_by=type). For the full list of endpoints see the endpoints index.