TLS & SSL

CAA Checker

Inspect a domain's CAA records to see which Certificate Authorities are allowed to issue TLS certificates, and find missing iodef contacts.

About this check

Audit CAA records, allowed CAs, wildcard policy, and iodef.

Frequently asked questions

What does the CAA Checker actually check?: Audit CAA records, allowed CAs, wildcard policy, and iodef.
Is this really free?: Yes. Every on.bo tool is free, no signup required, no rate-limit tricks.
Do you store the data I check?: We log minimal metadata to keep the service healthy. Lookups themselves are not retained beyond short-term caching.