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What are third-party origin trials?

What are third-party origin trials?

Origin trials are a way to test a new or experimental web platform feature. A third-party origin trial makes it possible for providers of embedded content to try out a new feature across multiple sites.

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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.

Diagram showing how third-party origin trials enable a single registration token to be usedacross 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. Getting 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.

How to 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.

How to provide 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, please create an issue on the Origin Trials GitHub code repo.

Find out more

Photo by Louis Reed on Unsplash.

Last updated: Improve article