Add new spec: The Idempotency-Key HTTP Header Field

[hamishwillee]

URL

https://datatracker.ietf.org/doc/html/draft-ietf-httpapi-idempotency-key-header/

Rationale

A slightly non-standard version of this is now being implemented on Firefox - currently behind a preference.

Specifically, this spec doesn't imply any browser integration - clients can apply the header in javascript based on whatever key information is desired/published out of band by the server. Firefox is proposing to add the header by default. It was due to be shipped but there are apparently compatibility issues on some sites that are being looked at.

I wanted this so that I could add a spec link from browser compatibility data - see mdn/browser-compat-data#28219. If this gets approved I'll add it after the fact.

Additional properties

{
  "nightly": {
      "repository": "https://github.com/ietf-wg-httpapi/idempotency",
      "sourcePath": "draft-ietf-httpapi-idempotency-key-header.md"
    }
}

[browser-specs-bot]

Changes to index.json

This update would trigger the following changes in index.json:

Add spec (1)

{
  "url": "https://datatracker.ietf.org/doc/html/draft-ietf-httpapi-idempotency-key-header/",
  "seriesComposition": "full",
  "shortname": "idempotency-key-header",
  "series": {
    "shortname": "idempotency-key-header",
    "currentSpecification": "idempotency-key-header",
    "title": "The Idempotency-Key HTTP Header Field",
    "shortTitle": "The Idempotency-Key HTTP Header Field",
    "nightlyUrl": "https://www.ietf.org/archive/id/draft-ietf-httpapi-idempotency-key-header-07.html"
  },
  "nightly": {
    "url": "https://www.ietf.org/archive/id/draft-ietf-httpapi-idempotency-key-header-07.html",
    "status": "Editor's Draft",
    "repository": "https://github.com/ietf-wg-httpapi/idempotency",
    "sourcePath": "draft-ietf-httpapi-idempotency-key-header.md",
    "alternateUrls": [],
    "filename": "draft-ietf-httpapi-idempotency-key-header-07.html"
  },
  "organization": "IETF",
  "groups": [
    {
      "name": "Building Blocks for HTTP APIs Working Group",
      "url": "https://datatracker.ietf.org/wg/httpapi/"
    }
  ],
  "title": "The Idempotency-Key HTTP Header Field",
  "source": "ietf",
  "shortTitle": "The Idempotency-Key HTTP Header Field",
  "categories": [
    "browser"
  ],
  "standing": "good"
}

Tests

These changes look good! 😎

Crawl results for draft-ietf-httpapi-idempotency-key-header-07

Crawl summary:

• Title: draft-ietf-httpapi-idempotency-key-header-07
• Date: 27 October 2025
• Canonical URL: https://datatracker.ietf.org/doc/html/draft-ietf-httpapi-idempotency-key-header/
• Spec defines:
  • Headings: 30 found
  • IDs: 372 found
  • Links: 25 rawlinks
  • References: 8 normative, 1 informative
• No Algorithms, CDDL, CSS, Events, Terms, Web IDL definitions found

[tidoust]

Seems good. I adjusted the URL and custom data. @browser-specs-bot pr

[hamishwillee]

Thank you very much @tidoust !