DigiCert is one of the world's largest enterprise certificate authorities with ~35% market share, serving 80%+ of the Fortune 100. It offers DV/OV/EV SSL/TLS certificates, code signing, and PKI solutions, known for its powerful CertCentral management platform and API automation.
Founded in 1996, GlobalSign is one of the world's longest-running commercial CAs serving 150+ countries. Offers full SSL/TLS certificates, enterprise managed PKI, IoT device identity, and document signing solutions.
SSL.com is a Houston Texas-based Certificate Authority founded in 2002, offering affordable DV/OV/EV SSL certificates from $39.95/yr, S/MIME, code signing, and enterprise PKI solutions.