Symantec is the world's largest digital certificate brand, focusing on security, encryption and security level, and is the first choice for major banks and financial investment and wealth management companies. China Construction Bank, China Bank, China Industrial and Commercial Bank and Bank of Communications all use Symantec SSL certificates.

GeoTrust is the second largest digital certificate brand in the world, with the highest cost performance and secure encrypted data. Zhihu is using GeoTrust's certificate.

GlobalSign is also a world-renowned digital certificate brand. In China, JD.COM, Taobao and Baidu all use his certificate.