Third-party origin trials

Providers of embedded content can test new or experimental web platform features.

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Origin trials are a way to test a new or experimental web platform feature.

Origin trials are usually only available on a first-party basis: they only work for a single registered origin. If a developer wants to test an experimental feature on other origins where their content is embedded, those origins all need to be registered for the origin trial, each with a unique trial token. This is not a scalable approach for testing scripts that are embedded across a number of sites.

Third-party origin trials make it possible for providers of embedded content to try out a new feature across multiple sites by providing a token using JavaScript.

Diagram showing how    third-party origin trials enable a single registration token to be used across multiple origins.

Third-party origin trials don't make sense for all features. Chrome will only make the third-party origin trial option available for features where embedding code on third-party sites is a common use case. Get started with Chrome's origin trials provides more general information about how to participate in Chrome origin trials.

If you participate in an origin trial as a third-party provider, it will be your responsibility to notify and set expectations with any partners or customers whose sites you intend to include in the origin trial. Experimental features may cause unexpected issues and browser vendors may not be able to provide troubleshooting support.

Supporting third-party origin trials allows for broader participation, but also increases the potential for overuse or abuse of experimental features, so a "trusted tester" approach is more appropriate. The greater reach of third-party origin trials requires additional scrutiny and additional responsibility for web developers that participate as third-party providers.

Requests to enable a third-party origin trial may be reviewed in order to avoid problematic third-party scripts affecting multiple sites. The Origin Trials Developer Guide explains the approval process.

Check Chrome Platform Status for updates on progress with third-party origin trials.

Register for a third-party origin trial

  1. Select a trial from the list of active trials.

  2. On the trial's registration page, enable the option to request a third-party token, if available.

  3. Select one of the choices for restricting usage for a third-party token:

    1. Standard Limit: This is the usual limit of 0.5% of Chrome page loads.
    2. User Subset: A small percentage of Chrome users will always be excluded from the trial, even when a valid third-party token is provided. The exclusion percentage varies (or might not apply) for each trial, but is typically less than 5%.
  4. Click the Register button to submit your request.

  5. Your third-party token will be issued immediately, unless further review of the request is required. (Depending on the trial, token requests may require review.)

  6. If review is required, you'll be notified by email when the review is complete and your third-party token is ready.

    Chrome origin trials registration page for the Conversion Measurement API, with third-party matching checkbox selected.
    Registration page for the Conversion Measurement trial.

A third-party token must be provided in an external JavaScript file included via a <script> element: a third-party token won't work in a meta tag, inline script or HTTP header.

Provide a trial token programmatically

To take part in an origin trial, a page must provide a valid trial token. If you want a trial feature to be enabled on multiple sites where your code is embedded, use JavaScript to inject a token:

const otMeta = document.createElement('meta');
otMeta.httpEquiv = 'origin-trial';
otMeta.content = 'TOKEN_GOES_HERE';

Otherwise, you would need to get every site that embeds your code to provide a token with an HTTP header or in their HTML.

The demo at accesses an origin trial feature enabled by using a token provided by JavaScript from a different origin.

Share feedback

If you're registering for a third-party origin trial and have feedback to share on the process or ideas on how we can improve it, create an Issue on the Origin Trials GitHub repository.

Find out more

Photo by Louis Reed on Unsplash.

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