Origin Trials Guide for Web Developers

Origin trials allow developers to try out new features and give feedback on usability, practicality, and effectiveness to the web standards community. Your feedback is valuable input into the final decision about the feature design, or even whether we want to proceed with standardizing and enabling the feature by default. When a feature is available as an origin trial, you are able to register to have it enabled for all users on your origin for a fixed period of time. Note that when the trial finishes we will contact you with a request to provide this feedback.

Once your origin has opted into a trial of an experimental feature you can then build demos and prototypes that your friends and beta testing users can try for the duration of the trial without them needing to flip special flags in Chrome.

How do I enable an experimental feature on my origin?

You can opt any page on your origin into the trial of an experimental feature by requesting a token for your origin. After signing up for a trial, we will generate a token for your origin.

There are two ways to provide this token on any pages in your origin:

<meta http-equiv="origin-trial" content="**insert your token as provided in the developer console**">
Origin-Trial: **token as provided in the developer console**


If you have trouble configuring pages with your token, or need other help, please contact us at origin-trials-support@google.com.

How can I experiment with the new feature locally?

Each feature that is available as an origin trial can alternatively be enabled on individual machines by flipping the corresponding flag in about:flags. The correct flag depends on the feature, and should be mentioned in the blog post about that specific feature.

You can get started experimenting with the new feature on localhost either by flipping the flag locally or requesting an origin trials token for localhost.

What is the thinking behind origin trials?

An exploration of the motivations and reasoning behind origin trials is provided in the explainer. The TL;DR is that we strongly value the feedback of real web developers (that means you!) during the process of designing and standardizing new features. We believe origin trials provide a good way of encouraging that feedback, while being extremely careful that the experiments aren’t used by sites in production-critical roles or as if they’re finalized features.

What experimental features are currently available?

The developer console lists all of the currently available features.


1. How can I find out about new experiments when they become available?

Origin trials have a built-in safeguard that automatically disables an experimental feature if its usage exceeds a small percentage of all Chrome page loads. This is designed to prevent individual web sites, and large populations of the web, from depending on experimental features.

The standard usage limit for a trial is 0.5% of all Chrome page loads, based on the same statistics as in Chrome Status. The usage is measured in a way to allow for temporary spikes of higher usage. In rare exceptions, a trial may be approved for a higher usage limit, only when necessary to allow for more effective experimentation (e.g. statistical significance requires a larger sample size of page loads).

This means that large production sites can try out experimental features, but they must take care to limit usage to a suitable portion of their traffic.

### 20. What are the options for usage retrictions on tokens?

By default, tokens are issued without any usage restriction. This means that when a token is valid for a page, the experimental feature will always be enabled on that page (assuming it hasn’t been disabled for exceeding usage limits).

For some trials, there will be options for different usage restrictions when registering for a token. If available, the choices are: