December 2015: Let's Encrypt removes the cost barrier keeping HTTPS adoption at 39%. Five years later, it becomes the world's largest certificate authority, issuing 1.4 billion certificates annually and pushing global HTTPS adoption past 84%.
The infrastructure consequence nobody planned for: organizations now manage hundreds of thousands of certificates instead of dozens. Eighty-one percent have experienced certificate-related outages in the past two years. Average cost per incident: $11.1 million. Manual tracking processes built for annual renewals can't handle this volume.
April 2025's mandate reducing certificate lifespans to 47 days forces the automation question. What Let's Encrypt made ubiquitous, operational teams must now systematize at scale.