Lego

Let's Encrypt client and ACME library written in Go.

{{% notice important %}} lego is an independent, free, and open-source project, if you value it, consider supporting it! ❤️

This project is not owned by a company. I'm not an employee of a company.

I don't have gifted domains/accounts from DNS companies.

I've been maintaining it for about 10 years. {{% /notice %}}

Features

• ACME v2 RFC 8555
  • Support RFC 8737: TLS Application‑Layer Protocol Negotiation (ALPN) Challenge Extension
  • Support RFC 8738: issues certificates for IP addresses
  • Support RFC 9773: Renewal Information (ARI) Extension
  • Support draft-ietf-acme-profiles-00: Profiles Extension
• Comes with about [180 DNS providers]({{% ref "dns" %}})
• Register with CA
• Obtain certificates, both from scratch or with an existing CSR
• Renew certificates
• Revoke certificates
• Robust implementation of ACME challenges:
  • HTTP (http-01)
  • DNS (dns-01)
  • TLS (tls-alpn-01)
• SAN certificate support
• CNAME support by default
• [Custom challenge solvers]({{% ref "usage/library/Writing-a-Challenge-Solver" %}})
• Certificate bundling
• OCSP helper function