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.
Thawte is a well-known certificate authority founded in 1995 in South Africa, now a DigiCert sub-brand offering full DV/OV/EV SSL and code signing certificates, with OV starting at $80/yr and unique brand heritage in African SSL markets.
GeoTrust is DigiCert's mid-range SSL certificate brand featuring QuickSSL Premium rapid issuance and full DV/OV/EV coverage starting at $7/yr, ideal for small to medium websites needing brand trust below DigiCert's premium tier.