[agwa]

You can query logs directly using the API described in RFC 6962: https://datatracker.ietf.org/doc/html/rfc6962#section-4

You'll need a list of logs to query. Chrome publishes their log list at: https://www.gstatic.com/ct/log_list/v3/log_list.json

My company offers a higher-level API for querying by domain name: https://sslmate.com/ct_search_api/