What are some alternatives?
When comparing Digicert and SSL For Free, you can also consider the following products
Let's Encrypt - Let’s Encrypt is a free, automated, and open certificate authority brought to you by the Internet Security Research Group (ISRG).
VeriSign - VeriSign Authentication Services provides solutions that allow companies & consumers to engage...
ZeroSSL - FREE SSL certificates issued instantly online with Free SSL Certificate Wizard.
GlobalSign - GlobalSign offers a range of SSL Certificates with the strongest 2048 bit encryption and value add features to ensure your website is protected.
COMODO SSL - Buy your Comodo SSL certificates directly from the No.1 Certificate Authority powered by Sectigo (formerly Comodo CA). Fast service with 24/7 support. Over 20 years of SSL Certificate Authority!
GeoTrust - Guarantee online customer security with SSL certificates from GeoTrust. Purchase in bulk, manage multiple certificates & become your own Certificate Authority.