Overview
Let’s Encrypt is a nonprofit certificate authority issuing free publicly trusted TLS certificates via the ACME protocol, underpinning HTTPS for a large share of the public web.
Recent Developments
- 2026-10-07: Announced default 64-day certificate lifetimes on classic ACME profile effective 2026-02-10; staging test from 2026-10-14; last 90-day certs expire 2027-05-11 (2026-10-07-lets-encrypt-64-day-certs-official)
- Roadmap: 45-day default classic profile 2028-02-16; operators should adopt acme-protocol Renewal Information and renew at ~⅔ lifetime (~day 43 for 64-day certs)