The Optimizely Experimentation Chrome extension

  • Updated

This topic describes how to:

  • Install the Optimizely Experimentation Assistant Chrome extension
  • Use the extension to assess the readiness of your site for experimentation
  • Conduct more intensive QA sessions of your experiments before you launch them

The Optimizely Experimentation Assistant Chrome extension gives users more insight into the nature of any Optimizely Experimentation activity occurring on their site. It also provides access to a suite of easy-to-use debugging tools. Here's where to get it: 

We recommend using this tool in conjunction with other QA tools and techniques to test and vet your experiments in Optimizely Experimentation before you launch them.


  1. Click here or search for the Optimizely Experimentation Assistant Chrome extension in the Chrome web store.

  2. Click Add to Chrome to add the extension to your browser.

  3. Turn on the extension by clicking on the Optimizely logo to the right of the address bar. clipboard_e5a431f31c64f46375d6a3d23e2f251cc.png

  4. Follow the prompts to log in to your Optimizely Experimentation account. This fetches the list of projects and snippets you have permission to view.

  5. Go to the site where you are using Optimizely Experimentation and open the Chrome JavaScript console to view messages:

  • On Windows and Linux, press Control-Shift-J.

  • On Mac, press Command-Option-J.

Logging in to the Optimizely Experimentation Assistant extension authorizes you to use the extension for the projects related to your last-used account. If you believe the extension is warning you in error about not having the right permissions, we recommend trying the following:

  1. In a regular Chrome tab, log in to Optimizely Experimentation with the user you will log in with via Optimizely Experimentation Assistant
  2. Switch accounts in Optimizely Experimentation to the account you'd like to use the extension with
  3. Authorize the new account in the Optimizely Experimentation Assistant
    1. If you've never logged in, simply click Open Login Pop-up
    2. If you've already logged in, you can click on the Settings gear icon, then click Log Out
  4. Log in to Optimizely Experimentation again with the user from step 1

This should authenticate you with the most recent account. If you continue to experience trouble, please reference the Support section below.



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The Optimizely Experimentation Assistant extension is a suite of utilities and tools that includes a comprehensive console log screen. Users can use it to quickly assess several important factors:

  • Whether Optimizely Experimentation is installed on the page

  • What experiments and campaigns are currently active

  • Which variations you're bucketed into

  • Which Optimizely Experimentation pages are currently active

One-click debugging tools


With the Optimizely Experimentation Assistant, you also have access to a set of debugging tools that allow you to QA your experiment at a deeper level than the Preview tool:

Add test cookie

This allows you to create or remove a test cookie so you can target an audience to it. Essentially, this will set your experiment live in a way that ensures you are the only one seeing it.

Delete Optimizely Experimentation data in a current browser session

This option clears any Optimizely Experimentation-related cookies or local storage key values assigned during the current browsing session. This is helpful if you’ve already been bucketed into an experiment and you no longer want to see that variation.

Use Instant Snippet

This feature can decrease the time between saving and testing your changes when building experiments and campaigns. It does this by using the Amazon S3 version of our snippet, which usually updates right away and before our distributed CDN. This only changes the version for your local Chrome environment, so your users will continue to be served experiences from our Content Delivery Network.

Swap snippet

Swapping a snippet is useful if an Optimizely Experimentation snippet is already on the page, but you need to QA with a different snippet. For instance, you can use it if you want to swap the production Optimizely Experimentation snippet into your site and QA experiments in your own QA environment. A user must have access to the account the snippet belongs to in order to swap it.

Inject snippet

Injecting a snippet is useful if a webpage doesn't have an Optimizely Experimentation snippet on it and you want to add it. A user must have access to the account the snippet belongs to in order to swap it.

Always use a non-cached snippet

Checking this box enables you to immediately view changes you made in Optimizely Experimentation in your browser. This can be useful for several reasons:

    • It typically takes a few minutes for a change to propagate from your experiment in Optimizely Experimentation to Amazon’s servers and out to the CDN.

    • Custom snippets allow you to configure a longer TTL (time to live) for a snippet. The default setting is two minutes, but you may choose to select a longer TTL to match your users' session duration. Longer TTLs mean end users would have to fetch the Optimizely Experimentation snippet from the CDN less frequently, but Optimizely users have to wait longer to see changes to experiments.

Strip X-Frame-Options header

This removes any X-Frame Options headers from your site, enabling it to load in the Optimizely Experimentation Editor.

Disable console logging

Check this box to prevent logs from printing in your console.

Disable Optimizely Experimentation

By temporarily disabling Optimizely Experimentation, you can determine which changes are influenced by Optimizely Experimentation and which aren’t.

Keyboard Shortcuts

Save time by setting and using feature keyboard shortcuts. These can be set on the chrome://extensions/shortcuts page.



If you experience any issues with the Optimizely Experimentation Assistant Chrome extension, please contact support.