Standards
http://csrc.nist.gov/publications/ - National Institute of Standards and Technology (NIST)
Publications on following topics:
1. Computer Security
2. Cybersecurity Practice Guides
3. Computer Systems Technology
http://www.eicar.org/ - download anti-malware testfile over HTTP/HTTPS to test firewall encr/decr capability and antivirus functionality
https://www.ssllabs.com/ssltest/index.html - check website SSL specs
Check URL Category
Cisco: https://securityhub.cisco.com/web/submit_urls
Palo Alto: https://urlfiltering.paloaltonetworks.com/
Working with Certificates:
https://certificatetools.com/newui/