Literature discovery & review

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

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

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

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

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

Volunteer-run decentralized bibliographic database of economics research, fed by institutional archives and served through IDEAS, EconPapers, the Author Service, CitEc, NEP and MPRA

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

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

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

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

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