RFC 8246 · PROPOSED STANDARD · 2017
WED · 29 JUL 2026
HTTP Immutable Responses
Overview
RFC 8246, “HTTP Immutable Responses”, is a Proposed Standard document published in September 2017 by P. McManus. The canonical text is published by the RFC Editor.
Abstract
The immutable HTTP response Cache-Control extension allows servers to identify resources that will not be updated during their freshness lifetime. This ensures that a client never needs to revalidate a cached fresh resource to be certain it has not been modified.
What “Proposed Standard” means
An entry-level standards-track specification: stable, peer-reviewed and a solid basis for implementation, though it may still evolve before becoming an Internet Standard.
Read this RFC
The canonical text of RFC 8246 is hosted at rfc-editor.org. Available in TXT,HTML.
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