Free Security APIs

EmailRep is a free API that evaluates the risk and reputation of an email address in seconds.

FilterLists is a community-maintained directory API that catalogs hundreds of filter lists used by ad blockers and firewalls like uBlock Origin and Pi-hole.

The Microsoft Security Response Center (MSRC) API provides programmatic access to Microsoft's security update data, including CVEs, advisories, and patch information.

Mozilla's HTTP Observatory API scans websites and grades their HTTP security configuration, checking for headers like CSP, HSTS, X-Frame-Options, and more.

The National Vulnerability Database (NVD) API gives you access to the U.S.

The Passwordinator API generates random passwords with customizable complexity, length, and character sets.

PhishStats is a real-time phishing URL database that aggregates phishing site data from multiple sources.

The UK Police API provides open access to crime data, police force information, and neighborhood policing data across England, Wales, and Northern Ireland.