acme.sh vs Certbot

acme.sh is a free Unix shell ACME client for automating SSL/TLS certificate issuance, renewal, and installation. Its installer creates a daily cron job to check certificates and renew them when needed. Written purely in shell, it is compatible with Bash, dash, and sh; the README says general use needs neither Python nor root or sudo access. It supports ECDSA, RSA, SAN, and wildcard certificates, with validation modes including webroot, standalone, standalone TLS-ALPN, Apache, Nginx, DNS, DNS alias, stateless, and DNS persist. ZeroSSL is the default certificate authority. Listed alternatives include Let's Encrypt, SSL.com, Google Public CA, Actalis, Pebble strict mode, and any RFC8555-compliant CA. The project says API integrations cover most DNS providers. Renewal uses a CA’s ACME Renewal Information when available, with a 30-day fallback rule otherwise. Manual DNS mode cannot renew automatically because each renewal requires a new TXT record to be added by hand. Tested systems listed include macOS, Windows through Cygwin, FreeBSD, and multiple Linux distributions. The project is GPLv3 licensed and officially maintained by ZeroSSL; release tags from version 3.1.6 onward are signed with the maintainer’s SSH key, while earlier tags are unsigned.

Certbot is free, open-source software from the Electronic Frontier Foundation for enabling HTTPS on websites that administrators manage themselves. It obtains Let’s Encrypt certificates and can install them on a web server automatically in many cases. The command-line tool names Apache and Nginx integrations, along with webroot and standalone methods. DNS validation avoids requiring an inbound connection from Let’s Encrypt, so it does not depend on an existing HTTP site or an open port 80. Certbot renews certificates when less than one-third of their lifetime remains; for certificates lasting 10 days or less, renewal occurs when half their lifetime remains. It is generally run on a Unix-like server, often remotely over SSH, and is intended for administrators comfortable with command-line work on a dedicated server, VPS or cloud-hosted server. The project points users to its documentation and the Let’s Encrypt community forum for help.