Finding SSL Certificates:

Certdomainfinder https://github.com/amar-
myana/certdomainfinder/blob/master/README.md
Certgraph https://github.com/lanrat/certgraph
Certificate Search https://crt.sh
CERT Spotter https://sslmate.com/certspotter/api
Google Transparency Report:
Certificates
https://transparencyreport.google.com/https/certific
ates
Internet-Wide Scan Data
Repository
https://scans.io
OpenData Rapid7 https://opendata.rapid7.com
Purplepee.com https://purplepee.co
spyse_ SSL Lookup https://spyse.com/tools/ssl-lookup