Java client for ACME (Let's Encrypt)
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ACME Java Client build status maven central

This is a Java client for the Automatic Certificate Management Environment (ACME) protocol.

ACME is a protocol that a certificate authority (CA) and an applicant can use to automate the process of verification and certificate issuance.

This Java client helps connecting to an ACME server, and performing all necessary steps to manage certificates.

It is an independent open source implementation that is not affiliated with or endorsed by Let's Encrypt.


  • Fully supports the ACME v2 protocol up to draft 14
  • Supports the http-01, dns-01 and tls-alpn-01 challenges
  • Supports the acme-ip draft
  • Supports the acme-star draft for short-term automatic certificate renewal (experimental)
  • Easy to use Java API
  • Requires JRE 8 (update 101) or higher
  • Built with maven, packages available at Maven Central
  • Small, only requires jose4j and slf4j as dependencies
  • Extensive unit and integration tests




acme4j is open source software. The source code is distributed under the terms of Apache License 2.0.