lego vs Smallstep Certificate Manager

lego is an independent, free, open-source ACME client and Go library for obtaining, renewing, and revoking certificates. It supports wildcard and SAN certificates and can work with multiple ACME servers, including Let’s Encrypt and ZeroSSL. Validation choices include DNS-01, HTTP-01, TLS-ALPN-01, and DNS-PERSIST-01. The project lists more than 200 DNS providers, including Cloudflare, Amazon Route 53, Google Cloud DNS, and Azure DNS, with CNAME support enabled by default. Users can run lego from the command line or call it as a Go library. DNS credentials and settings are supplied through environment variables, with file references and dotenv files supported. Installation options include prebuilt binaries, Docker, package managers, and source. The maintainers look after the AUR and Snap packages; other listed packages are community maintained. The project lists support for ACME RFC 8555 and certificate validation and renewal extensions. It is licensed under MIT, and installing from source requires Go 1.25 or later. The project points to GitHub issues and discussions for help.

Smallstep Certificate Manager has no write-up on Specifiction yet; its figures are above.