HTTP Immutable Responses
RFC 8246

Approval announcement
Draft of message to be sent after approval:

From: The IESG <>
To: IETF-Announce <>
Cc:, The IESG <>,, Mark Nottingham <>,,,,
Subject: Protocol Action: 'HTTP Immutable Responses' to Proposed Standard (draft-ietf-httpbis-immutable-03.txt)

The IESG has approved the following document:
- 'HTTP Immutable Responses'
  (draft-ietf-httpbis-immutable-03.txt) as Proposed Standard

This document is the product of the Hypertext Transfer Protocol Working Group.

The IESG contact persons are Adam Roach, Alexey Melnikov and Ben Campbell.

A URL of this Internet Draft is:

Technical Summary

The immutable HTTP response Cache-Control extension allows servers to identify resources that will
not be updated during their freshness lifetime. This assures that a client never needs to
revalidate a cached fresh resource to be certain it has not been modified.

Working Group Summary

Nothing interesting to report here.

Document Quality

This document quickly gained broad interest within the Working Group, and then support. It has been
reviewed by a substantial number of participants, and implemented by Mozilla in Firefox, and by
Facebook and others on the server side. Microsoft and Squid have stated that they are in the
process of implementing.


Mark Nottingham is the document shepherd; Alexey Melnikov is the responsible Area Director.