Everything you need to know about the Litmaps database, Open Access metadata, article indexing, and how Litmaps sources and updates research articles.
📌 Jump to:
The Litmaps database: where does the data come from?
The Litmaps database has 270+ million research articles.
Litmaps lets you search for articles with Open Access Metadata. To maximize our coverage of the literature, we ingest data from multiple data providers. While we have a substantial dataset, it's important to note that there will still be absences from our catalog: some articles simply don't have their metadata listed on open access metadata repositories.
The list of datasets in Litmaps includes:
These providers include coverage of many common datasets including:
PubMed
arXiv
bioRxiv
medRxiv
Web of Science
Scopus
Microsoft Academic Graph
📌 Want to check publisher coverage? See some of the included publishers here.
Database size across top research platforms
What is open access metadata?
Open Access metadata includes all article details except for the full content of the paper. This includes:
Title
Publication date
Abstract
References & citations
Open Access means that the publisher has made this information publicly accessible. We're legally only able to index Open Access metadata, so we can't represent articles (or citations/references of articles) that don't have this supplied.
The Litmaps database uses articles with available Open Access metadata to search on and generate suggestions, to ensure the best coverage for your search.
Open Access (OA) articles are not the same as those with Open Access metadata. OA articles are a subset of literature whose actual paper contents are publicly accessible. Litmaps contains both OA articles and closed-access articles. You can paywalled literature in Litmaps by setting up LibKey on your account, connecting Litmaps to your institutional access.
Why is an article missing from the Litmaps database?
There are several reasons an article can be missing from the Litmaps database.
If an article is missing, possible reasons include:
✔ It lacks Open Access metadata, meaning Litmaps cannot legally index it.
✔ It has not yet been indexed by Semantic Scholar, OpenAlex, or Crossref.
✔ It is too new, and its citation/reference data has not been fully updated.
Can't find an article? Watch this video to learn why!
Why is an article missing citations or references?
Sometimes articles in Litmaps display a lower number of references and/or citations than an article is expected to have. This can be for several reasons:
✔ You're comparing the citations and references to other sites (i.e. Google Scholar) which calculate them differently.
✔ Those references/citations don't have Open Access metadata.
✔ Some newer articles may have a delay in their citations and references appearing.
✔ Citations of older articles by very recent articles may similarly have a delay before appearing.
✔ You're looking for a different version of the article, and the article you found in Litmaps is a different version of the article you seek.
What's the coverage of the Litmaps database?
The Litmaps database covers 270+ million articles across multiple disciplines, pulling data mainly from Semantic Scholar, OpenAlex, and Crossref.
A 2022 study in Scientometrics found that Semantic Scholar has the second-best subject coverage across 56 research databases (Gusenbauer, 2022). Since Litmaps integrates this data, its coverage is comparable to top-tier scientific databases.
📌 Looking for a specific subject area? Try filtering searches in Litmaps for better precision.
Why do I see duplicate articles in Litmaps?
Duplicate articles in Litmaps occur due to versioning issues and data inconsistencies from source providers. While a deduplication process removes most duplicates, some may still appear due to incorrect or multiple identifiers.
✔ How to handle duplicates:
Ignore them if they don't affect your research.
Report them to Litmaps for review.
How does Litmaps handle article versioning?
Research articles often exist in multiple versions (pre-prints, published versions, and revisions). Litmaps only displays the most recent version with the highest-quality metadata. If a newer version has missing fields, an older, more complete version may be shown instead.
📌 Want to compare different versions? Litmaps allows you to view them—here's how.
How does Litmaps handle poor-quality articles?
Litmaps' core search algorithm relies on citations, but citation-based searches can be biased due to citation hacking, predatory journals, and unreliable research—a challenge for all literature search tools.
✔ How Litmaps Maintains Quality:
Updates the database weekly to ensure accuracy.
Prioritizes the most recent, highest-cited versions of articles.
Offers multiple search algorithms, allowing users to search by semantic similarity rather than just citation connections.
This approach enhances transparency, reliability, and user control over research discovery.