TLS 1.3 encrypts the server's certificates. With that protection in place, we finally have the confidence that we can implement certificate compression without causing middlebox issues. Certificate compression is an IETF TLS WG draft ( and we plan on implementing that specification, supporting the Brotli algorithm.


Specification link

Specification currently under development in a Working Group

Status in Chromium


Enabled by default (tracking bug)

Consensus & Standardization

After a feature ships in Chrome, the values listed here are not guaranteed to be up to date.

  • No signal
  • No signal
  • No signals



This feature is negotiated with the TLS server for each connection. We have high confidence that advertising support for certificate compression will not cause problems itself because we often add new TLS extensions (and have active GREASEing of them). This feature will be transparent to web developers: if their server implements certificate compression it will save a few bytes of TLS handshake but everything will otherwise be the same.

Search tags

TLS certificate compression,

Last updated on 2021-08-19