Direct comparison
Openalex Vs Pubmed: Key Differences & Comparison | CASRAI
OpenAlex covers 250M+ works across all disciplines under CC0; PubMed indexes selective biomedical literature with MeSH controlled vocabulary. Neither replaces the other.
Side-by-side comparison
| Dimension | OpenAlex | PubMed / MEDLINE |
|---|---|---|
| Operator | OurResearch (formerly Impactstory), a non-profit organisation | US National Library of Medicine (NLM), National Institutes of Health (NIH) |
| Launch / origin | January 2022; succeeded Microsoft Academic Graph (retired December 2021) | MEDLINE indexing began 1966; PubMed web interface launched 1996; continuously updated |
| Disciplinary scope | All research disciplines: sciences, social sciences, humanities, arts, engineering, medicine | Biomedical, clinical, and life sciences; some public health, nursing, dentistry, and pharmacy |
| Indexing approach | Broad ingestion with entity disambiguation; not editorially selective; covers preprints, conference proceedings, books, datasets, and journal articles | Selective editorial indexing; journals must apply for MEDLINE inclusion and meet NLM quality criteria; MeSH terms manually assigned to each record by NLM indexers |
| Controlled vocabulary | Concept/topic tags assigned algorithmically; based on structured machine-learning classification; not a manually curated controlled vocabulary | MeSH (Medical Subject Headings): hierarchical controlled vocabulary maintained by NLM; enables precise, consistent retrieval across decades of literature |
| Open access status | OA status for each work via integrated Unpaywall data (gold, green, bronze, hybrid, closed) | PMC free full-text link where available; no systematic OA classification equivalent to Unpaywall |
| API access | Free REST API; bulk data download via Amazon S3 (CC0 licence); no subscription required | Free API via Entrez E-utilities; NCBI API key recommended for high-volume queries; no bulk download of full MEDLINE records without NLM data licence |
| Citation data | Citation counts and reference lists included for most works; sourced from Crossref and Semantic Scholar | Citation counts not provided in PubMed itself; researchers use iCite (NIH) for PubMed citation metrics |
| Best for | Cross-disciplinary bibliometrics, institutional publication reporting, OA compliance monitoring, CRIS integration, programmatic bulk analysis | Clinical and biomedical systematic reviews, drug/disease literature searches, evidence synthesis, population health research, MeSH-controlled precision retrieval |
Common questions
FAQ
Can OpenAlex replace PubMed for systematic reviews?+
Not for systematic reviews in clinical and biomedical fields. Systematic review methodology requires comprehensive, reproducible literature searches, and MEDLINE's MeSH controlled vocabulary is specifically designed for this purpose — allowing reviewers to capture all relevant papers on a topic regardless of how authors phrase their keywords. OpenAlex's algorithmic topic tags do not replicate MeSH precision. Cochrane and PRISMA guidelines specify MEDLINE/PubMed as a required database for systematic reviews in health and medicine. OpenAlex may supplement a PubMed search to capture preprints or non-indexed literature, but it does not replace it.
Is PubMed free to use?+
Yes. PubMed is freely available at pubmed.ncbi.nlm.nih.gov without subscription or registration. Access to full-text articles is separate and depends on the journal's OA status or institutional subscriptions. PubMed Central (PMC) provides free full text for articles mandated to be deposited there (NIH-funded research, Wellcome Trust–funded research, and others). The Entrez API (E-utilities) is also free, with higher rate limits for users who register for an NCBI API key.
Why are some biomedical articles in OpenAlex but not PubMed?+
PubMed indexes only journals that have applied for and been accepted into MEDLINE indexing. Preprints (e.g., bioRxiv, medRxiv) are not in PubMed, though PMC hosts some author manuscripts. Conference proceedings, books, and grey literature are largely absent from PubMed. OpenAlex ingests from a much wider range of sources including preprint servers, institutional repositories, and journals not in MEDLINE. This means OpenAlex has broader coverage but less selectivity — it may include articles from journals that have not met MEDLINE quality criteria.
Do both databases provide author disambiguation?+
OpenAlex integrates ORCID identifiers and applies its own author disambiguation algorithms to link works to author entities, which improves but does not perfectly solve the name disambiguation problem. PubMed includes author ORCID identifiers where journals supply them but does not perform independent author disambiguation — the same author with a common name may appear as multiple distinct entities in a PubMed author search. For author-level bibliometric analysis, OpenAlex's author disambiguation is more systematic.
Going deeper
