_clck Cookie: What It Is, Who Sets It, and Consent Rules

What the _clck Cookie Does on Your Site

The _clck cookie is a first-party analytics cookie that Microsoft Clarity sets to recognise a returning visitor across session recordings. Microsoft describes the _clck cookie as the cookie that "persists the Clarity User ID and preferences", so every visit of the same browser to your site carries the same Clarity user ID. Clarity joins the session recordings and heat map data of a returning visitor through that ID.

The _clck cookie works with the _clsk cookie. The _clck cookie identifies the visitor, and the _clsk cookie "connects multiple page views by a user into a single Clarity session recording", according to the Microsoft list of Clarity cookies.

Who Sets the _clck Cookie

Microsoft Clarity sets the _clck cookie through the Clarity tracking code, which loads a tag from www.clarity.ms and then clarity.js from scripts.clarity.ms. Microsoft Advertising sites load Clarity through the Universal Event Tracking (UET) tag as well, through a tag URL under www.clarity.ms/tag/uet/.

Clarity enforces consent signals for visits from the European Economic Area (EEA), the UK, and Switzerland since 31 October 2025, according to Microsoft. A scan by the TermsFeed website auditor from Germany on 9 October 2026 found the Clarity script running after the visitor accepted the consent banner. The same scan found no _clck cookie. Check the consent call of your consent banner first on a site with the same result. Then check the Clarity cookie setting, the storage choices of the visitor, and the browser console for script errors.

Read how Microsoft Corporation handles the data in the Microsoft Clarity privacy policy. Both documents appear in the sources at the end of this page.

Does the _clck Cookie Need Consent?

Yes, the _clck cookie needs consent in the EU and the UK, and needs no prior opt-in in California. The table gives the rule for each law.

The consent table describes what each law requires and is not legal advice. Whether a law applies to your site depends on where your visitors are, where your business is based, and how you set up Microsoft Clarity, such as the Clarity cookie setting and the Clarity consent signal.

The ePrivacy Directive requires consent before a site sets the _clck cookie. The General Data Protection Regulation (GDPR) sets the standard for that consent: freely given, specific, informed, and unambiguous.

The UK Privacy and Electronic Communications Regulations (PECR) exempt analytics cookies that produce aggregate statistics to improve the site. The exemption comes from the Data (Use and Access) Act 2025 and took effect on 5 February 2026. The exemption needs clear information for visitors and a simple and free way to object, according to the ICO guidance on the exceptions. The exemption allows no tracking or profiling of individual visitors. The vendor needs to act as your processor, and recordings of individual visitors and advertising purposes stay outside the exemption. Microsoft Clarity records the sessions of individual visitors, and the ICO lists recordings of individual visitors and the actions they took among the uses that need consent. The statistics exemption therefore does not cover the _clck cookie.

The California Consumer Privacy Act (CCPA) sets no general opt-in requirement before a site sets the _clck cookie. Visitors get no right to opt out of the _clck cookie while Microsoft Clarity acts as your service provider. The service provider role needs a contract that limits the use of the data to the service for your site.

Read how each law decides which cookies need consent in the EU ePrivacy Directive + GDPR guide, the UK PECR guide, and the California CCPA guide.

How to Block the _clck Cookie Until Visitors Accept

Block the _clck cookie by holding back the Clarity tracking code until the visitor accepts analytics cookies. TermsFeed Free Cookie Consent and TermsFeed Privacy Consent place Microsoft Clarity in the analytics category. Check whether an exemption applies to your own use of Microsoft Clarity in the consent rules for the _clck cookie.

<script type="text/plain" data-cookie-consent="tracking">
  (function(c,l,a,r,i,t,y){
    c[a]=c[a]||function(){(c[a].q=c[a].q||[]).push(arguments)};
    t=l.createElement(r);t.async=1;t.src="https://www.clarity.ms/tag/"+i;
    y=l.getElementsByTagName(r)[0];y.parentNode.insertBefore(t,y);
  })(window, document, "clarity", "script", "YOUR_PROJECT_ID");
</script>

Block the _clck Cookie With the Clarity Consent API

Send the answer of the visitor to Clarity with the consentv2 call, which takes analytics_Storage and ad_Storage. Clarity sets its cookies once consent is granted, according to the Microsoft documentation on the Clarity Consent API. Clarity works in no-consent mode, with no first-party or third-party cookies, while consent is denied.

Clarity sends data to Microsoft in no-consent mode as well, with a new ID for every page view. Hold back the whole tracking code instead to send nothing to Clarity before the visitor accepts.

<script type="text/plain" data-cookie-consent="tracking">
  window.clarity('consentv2', {
    ad_Storage: "denied",
    analytics_Storage: "granted"
  });
</script>

How to Verify That the _clck Cookie Waits for Consent

Verify the setup in a private window. Open Chrome DevTools, select the Application tab, and open Cookies. Click "I decline" on the consent banner and reload the page. The _clck cookie must not appear in the list until you accept analytics cookies.

How Long the _clck Cookie Lasts

The _clck cookie lasts 1 year (365 days). Safari caps the cookies that JavaScript sets at 7 days of Safari use without an interaction with your site, according to the WebKit team behind Safari.

Microsoft gives no lifetime for the _clck cookie in the Clarity cookie list, and the TermsFeed website auditor lists 1 year (365 days). Check the expiry in Chrome DevTools on your own site before you copy the lifetime into your Cookies Policy.

Cookies That Work Together With _clck

Microsoft Clarity sets 6 other cookies next to the _clck cookie in its current setup.

Scripts and Requests of Microsoft Clarity That Come With the _clck Cookie

The catalog lists 3 scripts, pixels, and data endpoints of Microsoft Clarity, which a cookie scanner or the Network tab of Chrome DevTools shows next to the _clck cookie. Block the main script, and the requests in the table stop with the main script.

Changes to the _clck Cookie

The catalog records 1 dated change that affect the _clck cookie. The newest change comes first.

_clck Cookie FAQs

Is _clck a necessary cookie?

No, the _clck cookie is not a strictly necessary cookie. Firstly, your site works the same for a visitor who refuses the _clck cookie. Secondly, Clarity uses the _clck cookie to join session recordings and heat maps, a purpose the ePrivacy Directive exemption does not cover. Thirdly, Microsoft itself waits for a consent signal before Clarity sets cookies for visitors in the EEA, the UK, and Switzerland.

What is the difference between _clck and _clsk?

The _clck cookie keeps the Clarity user ID of a visitor, and the _clsk cookie joins the page views of a single visit into 1 session recording. Clarity needs both cookies to show a returning visitor and a complete session in the Clarity dashboard.

Does Microsoft Clarity work without cookies?

Yes, Microsoft Clarity works without cookies in no-consent mode, with fewer features. Firstly, Clarity assigns a new ID to every page view while consent is denied. Secondly, Clarity then connects no page views into sessions and recognises no returning visitor. Thirdly, Clarity still sends the page view data to Microsoft. Hold back the tracking code to send nothing to Microsoft before consent.

What happens when a visitor rejects the Clarity cookies?

Clarity deletes any existing Clarity cookie for the website, ends the current session, and restarts tracking in no-consent mode, according to Microsoft. No-consent mode stays active on future visits until the visitor gives consent.