Useful websites for web developers

• KeyCDN Tools (site speed, perf, ip geo, ping, http/2 and brotli tests)
• MXToolbox (mx, smtp, ptr, dnskey, ipseckey, ip geo, http and dkim tests)
• Pingdom Tools (website, ping and traceroute)
• WiseTools (dns, spf, dkim, )
• DNSChecker or CekDNS (to check if your dns has propagated)

Bonus round:

• email check-auth@verifier.port25.com to get spf/dkim/domainkey test results emailed back to you