ThreatCluster
Threat intelligence: incident clusters, validated IOCs, CVEs, ransomware leak-site victims
UK Police data.
UK Police API is a free Security API that requires no API key, is served over HTTPS and has unconfirmed CORS support.
Details from data.police.uk.

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Threat intelligence: incident clusters, validated IOCs, CVEs, ransomware leak-site victims
Virushee file/data scanning
The UK Police API is provided by data.police.uk (data.police.uk).
Yes. The UK Police API is listed in the Security category of the public-apis directory, which only includes APIs that are free or have a free tier. Check its documentation for rate limits and paid plans.
No. The UK Police API requires no authentication, so you can start making requests without signing up.
CORS support for the UK Police API is unknown. Test a request from the browser, and fall back to a server-side call if it is blocked.
Yes. The UK Police API is served over HTTPS, so it's safe to use in production.