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FF145 Experimental Features: Idempotency-Key #41698

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Oct 31, 2025
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FF145 Experimental Features: Idempotency-Key #41698

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FF145 ExprFeat: IdempotencyKey
hamishwillee Oct 27, 2025
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hamishwillee Oct 31, 2025
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20 changes: 20 additions & 0 deletions files/en-us/mozilla/firefox/experimental_features/index.md
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Expand Up @@ -731,6 +731,26 @@ When `Integrity-Policy` is used, the browser blocks the loading of styles refere
- `security.integrity_policy.stylesheet.enabled`
- : Set to `true` to enable.

### Idempotency-Key

The {{httpheader("Idempotency-Key")}} HTTP request header can be used by website client code to make a {{HTTPMethod("POST")}} or {{HTTPMethod("PATCH")}} requests {{glossary("idempotent")}} when used with a server that supports it.
The specification indicates that the server should document and advertise which endpoints require this header, the format of the key, and expected error responses.

Firefox _automatically_ adds the header with a unique key for each new `POST` request if it has not already been added by the page client-side code.
This simplifies the client-side code required to work with servers that support the feature.

([Firefox bug 1830022](https://bugzil.la/1830022)).

| Release channel | Version added | Enabled by default? |
| ----------------- | ------------- | ------------------- |
| Nightly | 135 | No |
| Developer Edition | 135 | No |
| Beta | 135 | No |
| Release | 135 | No |

- `network.http.idempotencyKey.enabled`
- : Set to `true` to enable.

### Accept header with MIME type image/jxl

The HTTP [`Accept`](/en-US/docs/Web/HTTP/Reference/Headers/Accept) header in [default requests and image requests](/en-US/docs/Web/HTTP/Guides/Content_negotiation/List_of_default_Accept_values) can be configured via a preference to indicate support for the `image/jxl` MIME type.
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