FedCM Binding of OIDC?

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Originally submitted by Nat (Nat Sakimura) on 2025-05-23

As I understand, FedCM could be another binding for OpenID Connect.

Account Endpoint looks quite similar to UserInfo Endpoint.

ID assertion endpoint looks quite similar to Token Endpoint.

Of course, there are a bunch of differences but there are similarities as well. For example, scope can also be sent, fields is used instead of claims, token that is returned could be ID Token. etc. There is no client credentials either.

Has any of you contemplated on it?

Google apparently migrated much of Sign in with Google to FedCM and Firefox is also implementing it.

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Bitbucket status: new

Bitbucket origin: issue 2179

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Originally submitted by Aaron Parecki (Aaron Parecki) on 2025-05-23

Yes, I wrote up detailed notes on how to do it here:

https://github.com/aaronpk/oauth-fedcm-profile

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Originally submitted by gffletch (gffletch) on 2025-07-31

I think it’s very important that we define a “FedCM binding for OpenID Connect”. My understanding of FedCM today (and Mozilla’s FedCM Lite) do not require OpenID Connect for SSO. It can be handled via the server side APIs identified for the identity provider (IDP).

I believe the foundation should work with the FedCM team and define the profile and the preferred way to connect FedCM with an OpenID Provider.

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Originally submitted by mbj (Michael Jones) on 2025-08-04

We discussed this on the 4-Aug-25 working group call. We agreed that this is a good idea.

We would need a volunteer or volunteers to edit the spec. Aaron Parecki,@{557058:64689aae-f6d2-4db5-b56a-8b21020634d2} and Sam Goto are possible candidates who come to mind.

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Originally submitted by Aaron Parecki (Aaron Parecki) on 2025-08-04

I am happy to take the lead on this. I already have a solid start to it at the link above.

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Originally submitted by panva (Filip Skokan) on 2025-08-05

I am likewise happy to volunteer.

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Originally submitted by gffletch (gffletch) on 2025-08-05

Thanks Aaron. I’m happy to help as well.

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Originally submitted by Andrii Deinega (Andrii Deinega) on 2025-08-05

Will be happy to help with anything on this one (if it’s needed). I had FedCM on my radar for a long long time.

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