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Everything you need to switch from Optimizely Classic to X in one place: See the Optimizely X Web Transition Guide.

Optimizely Knowledge Base

Update your site's Content Security Policies (CSP) in Optimizely X

There are two versions of Optimizely
What version do you have?
Optimizely Classic
This is what the Optimizely Classic user interface looks like.
Optimizely X
This is what the Optimizely X user interface looks like.
. If you're using Optimizely Classic, check this article out instead.
relevant products:
  • Optimizely X Web Experimentation
  • Optimizely X Web Personalization
  • Optimizely X Web Recommendations

  • Replace the deprecated X-Frame-Options HTTP header with its successor, Content Security Policies
  • Set Content Security Policies (CSP) in a way that allows for your site to load in Optimizely's Editor

Having trouble loading your page into the Optimizely X Visual Editor? 

Many sites protect visitors from cross-site scripting (XSS), clickjacking, and other code injection attacks by adding an X-Frame-Options header. However, this can prevent Optimizely from loading your page into Editor. It also blocks Optimizely from running parts of the snippet on your pages or sending tracking information back to our servers.

For this reason, you may need to update your site to include Content Security Policy (CSP) header  in order to run Optimizely and keep your customers safe from outside attacks.

Implement Content Security Policies (CSP) in Optimizely X

X-Frame-Options is a deprecated web standard that has been succeeded by Content Security Policies, which allows for greater customization, including the ability to whitelist Optimizely and work with pages in the Editor.

For Optimizely X, add the following strings to your CSP header value:

frame-src a[your-account-id-here]
script-src 'self' *
connect-src * 
style-src 'unsafe-inline'

If you need to implement CSP in Optimizely Classic, see this article instead.

How the CSP headers work

Each of the five lines contained in the CSP header has a specific purpose:

frame-src a[your-account-id-here]

This enables your page to load in Optimizely’s Visual Editor and enables cross-domain behavioral targeting. If you don’t need cross-domain behavioral targeting, you can omit a[your-account-id-here] from this string.

script-src 'self' *

This enables the Optimizely client script, the preview mode client, and Optimizely geotargeting.

connect-src * 

This line enables the Optimizely X client to log events.


This allows the Optimizely client to load images that have been uploaded using the Visual Editor.

style-src 'unsafe-inline'

This is required for experiment CSS changes to be applied. It is also required to avoid a jQuery feature detection error for any jQuery versions below 1.8.3. 

Now your browser will allow your site and Optimizely to load your pages in an iframe, while blocking attempts from all other parties.

Features that require explicit whitelisting

Some features will not be available in Optimizely X unless script-src 'unsafe-eval' is included in the CSP headers. These features include audiences with custom Javascript conditions, and the Visual Editor (unless the CSP header is not served when loaded as an iframe on with the optimizely_editor=true query param).

To enable these features, simply add this line to your CSP header:

script-src 'unsafe-eval'

Because of the way Optimizely X embeds custom code (e.g. custom variation code, experiment Javascript, project Javascript) into the client, the entire client will fail to parse if the custom code is syntactically incorrect. The Optimizely snippet will then fail to run as a result of this uncatchable error.

Experiment custom code and conditional activation code are not checked for syntax in the UI. Use this tool to check the syntax of your custom code.

Example of a complete CSP directive

Once you've gone through the steps above, the set of directives in your Content Security Policies may look something like this:

default-src 'none'
frame-src a[your-account-id-here]
script-src 'self' *
connect-src *
style-src 'unsafe-inline'

Since you're likely to use other third-party tools in addition to Optimizely, your rules might look different. Make sure to test them thoroughly before going live with these restrictions.

You can soft-launch your changes in report-only mode so that the restrictions don't affect your visitors, but violations are collected (e.g. via so you can adapt and fine-tune your CSP.