This guide helps you understand the changes to your web application introduced by the Federated Credentials Management API (FedCM).
When FedCM is enabled the browser displays user prompts and no third-party cookies are used.
Privacy Sandbox for the Web and Chrome's removal of third-party cookies from the web introduce significant changes to Google Identity Services and user sign in.
FedCM enables more private sign-in flows without requiring the use of third-party cookies. The browser controls user settings, displays user prompts, and only contacts an Identity Provider such as Google after explicit user consent is given.
Before you begin
Check that your browser and browser version supports the FedCM API, updating to a newer version if necessary.
Before testing sign-in flows with third-party cookies blocked, open
chrome://flags and enable the experimental
feature. This step is only necessary until it becomes the default. Also, the
Third-party sign-in setting has to be enabled in Chrome.
Migrate your web app
Follow these steps to enable FedCM, evaluate potential migration impact, and if needed to make changes to your existing web application:
1. Add a boolean flag to enable FedCM when initializing using:
HTML, set the
2. Remove use of
getNotDisplayedReason() methods in your code.
To improve user privacy, the
google.accounts.id.prompt callback no
longer returns any Display Moment notification in the
PromptMomentNotication object. Remove any code that depends on the
Display Moment related methods. They are
3. Remove use of
getSkippedReason() method in your code.
While the Skip Moment,
isSkippedMoment(), would still be called from the
google.accounts.id.prompt callback in the
object, detailed reason wouldn't be provided. Remove any code that depends on
getSkippedReason() method from your code.
Note that the Dismissed Moment notification,
the related detailed reason method,
getDismissedReason(), are unchanged
when FedCM is enabled.
position style attributes from
The browser controls the size and position of user prompts, custom positions for One Tap on Desktop are not supported.
5. Update page layout if needed.
The browser controls the size and position of user prompts. Depending upon
the layout of individual pages, some content might be overlaid as custom
positions for One Tap on Desktop are not supported in any way such as
intermediate_iframes, customized iframe, and other creative ways.
Change page layout to improve the user experience when important information is obscured. Don't build your UX around the One Tap prompt even if you assume it is in the default position. Because the FedCM API is browser-mediated, different browser vendors may place the position of the prompt slightly differently.
allow="identity-credentials-get" attribute to parent frame if your web app calls One Tap API from cross-origin iframes.
An iframe is considered as cross-origin if its origin is not exactly the same as the parent origin. For Example:
- Different domains:
- Different top-level domains:
To improve user privacy, when One Tap API is called from cross-origin iframes, you must add
allow="identity-credentials-get"attribute in every parent frame
<iframe src="https://your.cross-origin/onetap.page" allow="identity-credentials-get"></iframe>
If your app utilizes an iframe that contains another iframe, you must ensure that the attribute is added to every iframe, including all sub-iframes.
For example, consider the following scenario:
The top document (
https://www.example.uk) contains an iframe named "Iframe A", which embeds a page (
This embedded page (
https://logins.example.com) also contains an iframe named "Iframe B," which further embeds a page (
https://onetap.example2.com) that hosts One Tap.
To ensure that One Tap can be displayed properly, the attribute must be added to both Iframe A and Iframe B tags.
Prepare for inquiries on the One Tap prompt not displayed. Other sites with different origins may embed your pages that host One Tap within their iframes. You may receive increased amount of support tickets related to One Tap not showing up from end-users or other site owners. While the updates can only be made by the site owners on their pages, you can do the following to mitigate the impact:
Update your developer documentation to include how to set up the iframe properly to call your site. You can link to this page in your documentation.
Update your developer FAQs page if applicable.
Let your support team know this upcoming change and prepare for the response to the inquiry ahead of time.
Proactively contact impacted partners, customers, or site owners for a smooth FedCM transition.
7. Add these directives to your Content Security Policy (CSP).
This step is optional as not all websites choose to define a CSP.
* If CSP is not used in your website, no changes are needed.
* If your CSP works for the current One Tap and you don't use
default-src no changes are
* Otherwise, follow this guide to set up your CSP. Without proper CSP
setup, the FedCM One Tap wouldn't be displayed on the site.
8. Remove Accelerated Mobile Pages (AMP) support for sign-in.
User sign-in support for AMP is an optional feature of GIS your web app may have implemented. If this is the case,
Delete any references to the:
amp-onetap-googlecustom element, and
<script async custom-element="amp-onetap-google" src="https://cdn.ampproject.org/v0/amp-onetap-google-0.1.js"></script>
Consider redirecting sign-in requests from AMP to your website's HTML sign-in flow. Note that the related
Intermediate Iframe Support APIis unaffected.