Add a note about back button and no-cache

[tunetheweb]

Description

Add a section to explain no-cache doesn't mean browsers will always revalidate.

Motivation

Developers are often confused when browsers reuse no-cache pages when they expect them to reload. For example:

• https://issues.chromium.org/issues/41192250#comment6
• https://www.mixmax.com/engineering/chrome-back-button-cache-no-store
• https://gertjans.home.xs4all.nl/javascript/cache-control.html

This came up again in an internal discussion and we realised this is not documented anywhere.

Additional details

Chrome and Firefox does this as can be seen from this test page.

Safari is difficult to confirm as they agressively use bfcache and everything I've tried to force it not to do that fails. Only no-store stops bfcache from being used by but that is not what I'm trying to test!

Related issues and pull requests

[tunetheweb]

@fergald FYI comments welcome!

[github-actions]

Preview URLs (2 pages)

• /en-US/docs/Web/HTTP/Guides/Caching
• /en-US/docs/Web/HTTP/Reference/Headers/Cache-Control

External URLs (2)

URL: /en-US/docs/Web/HTTP/Guides/Caching
Title: HTTP caching

• https://httpwg.org/specs/rfc7234.html (1 time) (Note! This may be a new URL 👀)

---

URL: /en-US/docs/Web/HTTP/Reference/Headers/Cache-Control
Title: Cache-Control header

• https://httpwg.org/specs/rfc7234.html (3 times) (Note! This may be a new URL 👀)

(comment last updated: 2026-06-29 23:44:04)

[hamishwillee]

Thanks @tunetheweb - very useful. I've subedited a little to my taste - mostly because I wanted to be even more direct about the unexpected case being the history navigations. I also duplicated the note in Cache-Control, because I think people might also search there.

1. Are you happy with those changes
2. Is there anywhere else we should highlight this? I was wondering if maybe also in https://developer.mozilla.org/en-US/docs/Web/API/History_API ?

[fergald]

I could be wrong but I thought this also impacted max-age. Someone said we behave like force-cache here

[tunetheweb]

Thanks @hamishwillee . I wasn't loving your last sentence (it seems to imply using back DOES use the HTTP cache outside of bfcache), so tweaks that a little further.

I don't think this needs to be on the History API page. It doesn't discuss other caching directives. So think these two pages are sufficient.

PTAL and merge if good!

@fergald I added a similar comment to max-age and must-revalidate sections. It's a little repetitive but think that's the best way.

[hamishwillee]

Lets remove this and put above in note - it is then directly stated it applies.

[hamishwillee]

Thanks @hamishwillee . I wasn't loving your last sentence (it seems to imply using back DOES use the HTTP cache outside of bfcache), so tweaks that a little further.

@tunetheweb I wasn't loving your last sentence either - very hard to parse. However I've restructured this and I am pretty sure we'll both be happy.

[hamishwillee]

LGTM to me.