ACME Automatic Certificate Management Environment
More info
- Released
- Type
- Protocol
- Spec
- RFC 8555
The protocol that automates issuing and renewing TLS certificates.
The client requests a certificate and the server responds with a challenge proving domain control: http-01 places a file under /.well-known/acme-challenge/, dns-01 sets a TXT record (the only route to wildcard certificates), tls-alpn-01 answers during the handshake.
Written for Let's Encrypt and standardised as RFC 8555 (2019). Several CAs now support it, and Caddy and Traefik perform the whole dance automatically with no configuration.