20 Free Security APIs Every Developer Should Know About (2026)

I spent the last month cataloging every free security API I could find. Here are the 20 best ones — each with a free tier generous enough for real projects. I also built Python tools for the most useful ones. All open-source. The Full List Vulnerability Databases 1. NVD (National Vulnerability Database) 250,000+ CVEs, maintained by NIST No key needed (optional key for higher limits) Tutorial | Python Tool 2. OSV.dev Google's open-source vulnerability database No key, no rate limits Covers npm, PyPI, Go, Rust, and more 3. GitHub Advisory Database Security advisories for GitHub ecosystem Free with GitHub token (5,000 req/hr) Malware & Threat Intelligence 4. VirusTotal Scan against 70+ antivirus engines 500 lookups/day free Tutorial | Python Tool 5. AlienVault OTX 200,000+ contributors sharing IOCs No rate limits Tutorial 6. MalwareBazaar (abuse.ch) Malware sample database No key needed Download actual samples for research 7. URLhaus (abuse.ch) Database of malicious URLs No key, no rate l