Third-party origin trials in context

Chrome's origin trials let developers test experimental web platform features before they ship broadly. A trial is normally registered against a single origin. That works well for a site testing its own feature, but it becomes a problem when you build embedded content — a script, widget or iframe that runs on many different sites. To test the feature on each of those sites, every one of those origins would have to register separately and obtain its own unique trial token. That doesn't scale for providers whose code is widely embedded.

Third-party origin trials solve this by letting one provider register a token that works across the multiple sites where their content is embedded.

This option is only relevant for features where third-party embedding is a common pattern; Chrome won't offer third-party tokens for every trial. Getting started with Chrome's origin trials covers the general registration process and participation requirements. Note that if you participate as a third-party provider, you're responsible for informing any partner or customer sites you include in the trial and setting their expectations. Experimental features can break unexpectedly, and browser vendors may not offer troubleshooting support. Progress on third-party origin trials is tracked on Chrome Platform Status.

Registering a third-party token

  1. Pick a trial from the list of active trials.
  2. Open the trial's registration page and, if available, enable the third-party token option.
  3. Choose a usage restriction for the third-party token:
    • Standard Limit: the default 0.5% cap on Chrome page loads.
    • User Subset: a small percentage of Chrome users — usually less than 5%, though it varies per trial — will never be included, even with a valid token.
  4. Submit the request using the Register button.
  5. Your third-party token is issued immediately unless the trial requires further review.
  6. If review is required, you'll be emailed once the review finishes and your token is ready.

Feedback and resources

If the registration process itself needs improvement, file an issue on the Origin Trials GitHub repo.

Useful references: