Direct comparison
Google Scholar vs. Web of Science
Curated vs. crawled: how Google Scholar and Web of Science differ in indexing criteria, citation counts, coverage, cost, and API access.
Side-by-side comparison
| Dimension | Google Scholar | Web of Science |
|---|---|---|
| Owner / access model | Google. Free to search, no subscription required. | Clarivate. Paid subscription, typically via an institutional library. |
| Indexing method | Automated crawling of the open web; no formal editorial review of sources. | Editorially curated Core Collection (SCIE, SSCI, AHCI, ESCI, Conference Proceedings Citation Index, Book Citation Index); journals must pass Clarivate’s selection criteria and can be delisted. |
| Content types indexed | Journal articles, preprints, theses/dissertations, patents, conference papers, books, grey literature — whatever crawlers can parse as scholarly. | Peer-reviewed journal articles, books, and conference proceedings that have cleared editorial evaluation. |
| Citation-counting methodology | Counts citations from any indexed document, including non-peer-reviewed sources; no published deduplication methodology; counts can fluctuate as the crawl updates. | Counts citations only from sources within the Core Collection; smaller, more consistent, and auditable against a defined index. |
| Typical citation counts for the same paper | Generally higher, since the citing universe is broader. | Generally lower, since only Core Collection sources count. |
| Author h-index | Computed from Scholar’s broader citation set — typically higher than the same author’s Web of Science h-index. | Computed from Core Collection citations only — typically lower, but tied to a defined, citable index. |
| Official API | None. No official public API; ToS prohibits scraping; third-party "Google Scholar API" products are unofficial scrapers. | Yes — documented, subscription-tier APIs (Expanded API, Starter API) for institutional programmatic access. |
| Best suited for | Broad literature discovery, grey literature, preprints, quick individual citation checks, public researcher profiles. | Funder/tenure reporting requiring an editorially-vetted source, journal Impact Factor lookups, structured bibliometric analysis. |
Common questions
FAQ
Why do Google Scholar and Web of Science show different citation counts for the same paper?+
Web of Science only counts citations from sources inside its editorially-curated Core Collection. Google Scholar counts citations from anything its crawler indexed as scholarly, including preprints, theses, and non-peer-reviewed material — a much broader universe that produces higher counts.
Is Google Scholar or Web of Science better for citation counts?+
Neither is unconditionally "better" — it depends on the purpose. Web of Science counts are narrower but auditable against a defined, editorially-vetted index, which is what most funders and tenure committees that specify "Web of Science-indexed" citations actually want. Google Scholar counts are broader and free, useful for a fast individual check or for capturing grey-literature impact, but harder to defend as a consistent, reproducible metric.
Does Web of Science cost money?+
Yes. Web of Science is a paid Clarivate product, almost always accessed through an institutional library subscription rather than purchased individually. Google Scholar is free to search with no subscription.
Is there an official Google Scholar API?+
No. Google has never released an official, documented public API for Google Scholar. Products marketed as a "Google Scholar API" are unofficial third-party services that scrape Scholar’s public pages, which Google’s Terms of Service and robots.txt both restrict.
Going deeper
