#1147: WG New Spec: FedCM—Support Structured JSON Responses from IdPs

Visit on Github.

Opened Sep 5, 2025

Specification

https://github.com/w3c-fedid/FedCM/pull/771

Explainer

https://github.com/w3c-fedid/FedCM/blob/main/explorations/structured_data_support.md

Links

The specification

Where and by whom is the work is being done?

  • GitHub repo: https://github.com/w3c-fedid/FedCM
  • Primary contacts:
  • Suresh Potti ( @pottis), Microsoft, feature author
  • Nicolás Peña Moreno (@npm1), Google, spec editor
  • Organization/project driving the specification: Google/Microsoft
  • This work is being funded by: Google/Microsoft
  • Primary standards group developing this feature: W3C Federated identity working group
  • Incubation and standards groups that have discussed the design: n/a
    • {{ABC CG}} <!-- Include a link to minutes or issues in this group if possible. -->
    • {{DEF WG}}

Feedback so far

You should also know that...

No response

<!-- Content below this is maintained by @w3c-tag-bot -->

Track conversations at https://tag-github-bot.w3.org/gh/w3ctag/design-reviews/1147

Discussions

Log in to see TAG-private discussions.

Discussed Oct 13, 2025 (See Github)

Lola: Jeffrey proposed to close this, as it’s a minor thing and they’ve got the expertise for it. It is also so small that I don’t understand the benefit of a review. This essentially changes a property from a string to structured JSON data. They are changing it to accept both of which. Serialization/deserialization seems easy in JavaScript though. Jeffrey: Think it is super minor. One reason we shouldn’t try to second-guess them. They talked to developers, they seem to be happy, so they should be able to make that change cheaply. Lola: That was my inclination as well. @Jeffrey, what is the benefit to decline? Jeffrey: Want them to improve the quality of the reviews.

Comment by @lolaodelola Oct 13, 2025 (See Github)

Hi @pottis,

Thanks for submitting this for review, please update the explainer link to point to the full explainer; it seems that lives here: https://github.com/w3c-fedid/FedCM/blob/main/explorations/structured_data_support.md

Comment by @pottis Oct 17, 2025 (See Github)

Updated the link. Thanks.

Discussed Oct 20, 2025 (See Github)

Lola: Jeffrey's OK'd my proposed comment - any other thoughts? It's a minor update to support structured datatypes as well as strings. Suggestion made that we should decline to review; that's where my comment's leaning.

Discussed Oct 27, 2025 (See Github)

closed

Comment by @lolaodelola Oct 28, 2025 (See Github)

Hi @pottis,

Thank you for requesting a review for this update, however, this is a minor change that has been fully discussed in the appropriate working group and we trust that the working group's decision to support structured data in addition to string.

We don't see any evidence that the working group has asked us to review the FedCM specification. In future, please use the 'Other Specification Review' issue template for reviews for features that don't yet have the working group's endorsement. When you are ready to open a review for the spec or if other features need to be reviewed, please also submit requests for Mozilla and WebKit's position on the spec/feature.