A Decade of Let’s Encrypt: Free, Automated TLS Became the Default

Let’s Encrypt turns ten, and the scoreboard says it all: billions of certificates issued, hundreds of millions active, and the share of web traffic served over HTTPS now the norm rather than the exception. What’s notable here isn’t a nostalgic milestone but the normalization of automation. By standardizing the ACME protocol and making DV certificates free and renewable by API, Let’s Encrypt collapsed the cost and toil that kept TLS adoption uneven. That, in turn, made “TLS by default” the baseline expectation for new software, CDNs, and frameworks-less hype, more plumbing.

Under the hood, the project pushed several technical shifts that stuck: short 90-day lifetimes that encourage automation, multiple validation methods (HTTP-01, DNS-01, ALPN-01), multi-perspective domain checks to blunt routing/DNS hijacks, and universal Certificate Transparency logging. The move to ECDSA chains trimmed handshake sizes and CPU, helping at scale. Worth noting: an open CA stack (Boulder), mature client tooling (from Certbot to built-in integrations in servers and proxies), and a donor-funded model reshaped CA economics, pressuring the market to treat basic DV as a commodity. The bigger picture is simple: by removing friction at issuance and renewal, Let’s Encrypt turned transport encryption into a background feature. That freed teams to focus higher up the stack-where the remaining hard problems actually live.