Origin Trials
Mozilla Firefox Origin Trials are a way for websites to opt-in to experimental web platform features.
Current Trials
Currently active trials are:
- MLS (Messaging Layer Security): Enables the `window.MLS` experimental API.
- Submit feedback for this feature: ...
- COEP: credentialless: Enables the `credentialless` value for the `Cross-Origin-Embedder-Policy` header.
- COEP: credentialless is enabled in Firefox Desktop by default since Firefox 119, you only need to request an origin trial if you need it for Firefox Android.
- Submit feedback for this feature: https://github.com/whatwg/html/issues?q=state%3Aopen%20label%3A%22topic%3A%20cross-origin-embedder-policy%22
- Privacy Preserving Attribution: See intent to experiment.
- Submit feedback for this feature: https://github.com/w3c/attribution/issues/
Requesting a trial for your website
In order to request a trial please click here:
That will take you to Bugzilla with an already-prefilled template where you'd need to fill a few details (like trial name, website origin, whether subdomains should be included, and a suggested expiration date / other details if you know them). A token will be given to you in that bug.
Using the trial token
Once you get a reply with a token, you can use them by serving your page with the relevant header:
origin-trial: your-token
Or with a meta tag:
<meta http-equiv="origin-trial" content="your-token">
Submit feedback
During the time a feature is in Origin Trial, feedback from web developers can be addressed without risk of breaking compatibility with widely deployed web content. After a feature has shipped it is usually harder to make breaking changes.
When you have some experience with using a feature in Origin Trial, please send any feedback about the feature's design, usability, or developer experience by filing a spec issue. Links are provided above under Current Trials. Thank you!
Example issue template:
I have used <feature name> via Firefox's Origin Trial on my website. Here is my feedback: * ...
Articles
Articles and blog posts about Origin Trials in general:
- 2020-10-28 Stephanie Stimac: What the heck is an Origin Trial?
Origin Trials are a way for developers to test and use experimental web platform features for a limited amount of time in exchange for feedback. Feedback is key in origin trials as browsers are granting developers access to ensure that the feature makes sense and is usable.
- ...
Other Browsers Origin Trials
Documentation and lists of origin trials in other browsers: