Crossref API: Search 150M+ Academic Papers for Free (No API Key Needed)

The Problem: Academic Research Data Is Locked Behind Paywalls Last month, a data scientist asked me: "How do I get citation data for 1000 papers without paying $50,000 for a Web of Science subscription?" My answer: Crossref API — 150M+ metadata records, completely free, no API key required. What Is Crossref? Crossref is the backbone of scholarly publishing. Every time a journal assigns a DOI, Crossref stores the metadata. That means: 150M+ works (papers, books, conferences) Citation links between papers Funding data — who paid for the research License info — is it open access? All free, all via REST API Quick Start: Search Papers in 3 Lines import requests results = requests . get ( " https://api.crossref.org/works " , params = { " query " : " machine learning drug discovery " , " rows " : 5 , " sort " : " relevance " }). json () for item in results [ " message " ][ " items " ]: title = item [ " title " ][ 0 ] if item . get ( " title " ) else " No title " cited = item . get ( " is-refe