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Semantic Scholar

by Allen Institute for AI (Ai2) · Service · also known as S2, Semantic Scholar Academic Graph, S2AG

Free AI-assisted literature search from Ai2 with an Academic Graph API, recommendations and downloadable datasets of papers, authors and citations

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Link verified Nov 2, 2026

Overview

Semantic Scholar is a free scholarly search engine and data platform built by the Allen Institute for AI (Ai2). The web product indexes well over two hundred million papers across fields and adds machine-generated aids such as short summaries, citation context and an augmented PDF reader (Semantic Reader) alongside a personal library and feeds.

For programmatic use, the Semantic Scholar API has three services: the Academic Graph API for papers, authors, citations, venues and SPECTER2 embeddings; a Recommendations API that returns papers similar to a seed paper; and a Datasets API that serves bulk snapshots of the academic graph. Most endpoints work without authentication under a shared public rate limit; a free API key requested through a form raises the limit and is recommended for sustained use.

Use of the data is governed by the license attached to each dataset (the license page cites CC BY-NC and ODC-BY as examples), and the API agreement prohibits repackaging or reselling the API itself and asks for attribution to Semantic Scholar in products and publications. Because coverage is built from publisher feeds and crawls, metadata quality varies by field, and heavy unauthenticated use is throttled.

Capabilities

  • Search over a corpus of hundreds of millions of papers
  • Academic Graph API for papers, authors, citations and venues
  • Recommendations API for similar papers
  • Bulk dataset snapshots (S2AG) for offline analysis
  • SPECTER2 paper embeddings
  • Semantic Reader augmented PDF reading

Typical workflows

  1. Building a citation network for a literature review
  2. Enriching a reference list with abstracts and citation counts via the API
  3. Training or evaluating retrieval models on S2AG snapshots

Strengths

  • Free for public use with documented API
  • Bulk datasets available for research
  • Operated by a non-profit research institute

Limitations

  • Unauthenticated requests share a public rate limit
  • Dataset licenses vary and some restrict commercial use
  • Coverage and metadata quality differ across disciplines

Prerequisites

  • Free API key for sustained programmatic use

Who it is for

  • Researchers doing literature reviews
  • Developers of scholarly tools
  • NLP and scientometrics researchers

Alternatives & comparison

OpenAlex releases its whole catalog under CC0 with a metered API, whereas Semantic Scholar's datasets carry per-dataset licenses that may be non-commercial; Google Scholar offers no API at all. Connected Papers and ResearchRabbit build visual exploration on top of graphs like this one.

  • arXiv

    Free, moderated open-access preprint server for physics, mathematics, computer science, statistics, quantitative finance, economics and related fields, with an open API and bulk access

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  • Connected Papers

    Visual literature-exploration tool that builds a similarity graph of papers around a seed paper, with prior and derivative works lists

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  • Consensus

    AI search engine over peer-reviewed literature that synthesizes answers, shows a Consensus Meter for yes/no questions and summarizes studies

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  • Crossref

    Membership organization that registers DOIs for scholarly content and exposes the metadata through a free public REST API, content negotiation and the paid Metadata Plus service

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  • Elicit

    AI research assistant that finds papers, extracts structured data from them into tables and runs systematic-review style workflows and reports

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  • Google Scholar

    Free scholarly search engine from Google that indexes articles, theses, books and court opinions with citation counts and author profiles

    ProprietaryFree
  • OpenAlex

    Open catalog of the global research system: works, authors, sources, institutions and topics under CC0, served by a REST API, web app and S3 snapshot

    Open sourceFree
  • ResearchRabbit

    Literature-discovery app that grows collections of papers through citation and author networks and recommends related work, with a free-forever tier

    ProprietaryFreemium
  • scite

    Citation-analysis platform whose Smart Citations show whether later papers support, contrast or merely mention a claim, with an AI assistant and reference checking

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Sources & verification

Primary sources consulted for this record. Claims are tied to the fields each source supports; the automated link checker re-verifies every URL on a schedule.

Confidence
High
Reviewed
Nov 1, 2026
Links
Verified · Nov 2, 2026

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