Microsoft Clarity

What Is Microsoft Clarity?

Microsoft Clarity is a free behavior-analytics tool that gives website owners heatmaps, session recordings, and frustration insights without charging a cent or limiting how much data they capture. Launched by Microsoft in 2020, Clarity disrupted the experience-analytics market by offering capabilities, unlimited session replays, click and scroll heatmaps, and automated friction detection, that competitors typically put behind paid tiers. Microsoft has reported that Clarity is used on millions of sites and processes data on a massive scale, which is exactly why it now appears so often when you inspect what technology a website is running.

A note on categorization: in StackOptic's taxonomy Clarity is filed under the "ui" category rather than "analytics," because its primary value is improving the user interface and on-page experience through visual behaviour insight. Functionally it is a sibling of Hotjar and other behavior-analytics tools, the difference is that Clarity is entirely free, with no sampling caps, no recording limits, and no credit card required.

Clarity's appeal is straightforward. For teams that want to watch how real users navigate their site, spot where people rage-click or hit dead ends, and see which parts of a page actually get attention, Clarity removes the cost barrier completely. Microsoft funds it as part of its broader advertising and web ecosystem, and integrates it with Google Analytics and Microsoft Advertising, but the core tool is free and privacy-conscious by design.

How Microsoft Clarity Works

Clarity operates through a single lightweight tracking script, similar in spirit to other behavior-analytics tools but notably small and fast.

When a site signs up, Clarity assigns a unique project ID (an alphanumeric string). The owner installs the Clarity snippet, which loads the tracking tag from www.clarity.ms/tag/<project-id> and defines a global function named clarity used to queue events and configuration. The snippet is asynchronous and intentionally lightweight to minimize performance impact.

Once running, Clarity captures:

Session recordings. Clarity reconstructs visits by recording the page's DOM and user interactions, mouse movement, clicks, taps, scrolls, navigation, and replays them as session recordings. Crucially, this is unlimited on every account; there is no sampling cap, so high-traffic sites can record effectively all sessions. Sensitive content is masked by default.

Heatmaps. Click, scroll, and area heatmaps visualize aggregate engagement, showing which elements attract attention and how far visitors scroll. Clarity's heatmaps work across device types and can be segmented.

Insights and smart events. Clarity automatically detects friction signals it calls out by name, including rage clicks (rapid repeated clicking on one spot), dead clicks (clicks on non-interactive elements), excessive scrolling, quick backs (immediately leaving and returning), and JavaScript errors. These automated insights surface usability problems without manual analysis.

AI-assisted summaries. Clarity has added AI features (built on Microsoft's models) that summarize session data and answer plain-language questions about user behaviour.

All captured data is sent as beacons to Clarity's servers under the clarity.ms domain, processed, and presented in the Clarity dashboard. Clarity also offers a native integration with Google Analytics, so recordings can be linked to GA segments, and with Microsoft Advertising for campaign insight.

Like other modern session tools, Clarity reconstructs visits from the DOM and an event timeline rather than recording literal video, which keeps the script lightweight and lets it mask sensitive content before it leaves the browser. Microsoft documents three masking modes, strict, balanced, and relaxed, that control how aggressively text and input values are hidden, with the default favouring privacy. This matters for detection: because Clarity respects consent and masking settings, the _clck and _clsk cookies and the clarity.ms beacons may only appear after a visitor accepts a cookie banner, so a consent-aware scan is more dependable than a single glance at the source.

A defining technical choice is that Clarity does not sample. Where paid tools cap how many sessions they record per month, Clarity is engineered to ingest data at very large scale and replay effectively every session, which is the main reason high-traffic sites adopt it. The trade-off is that Clarity keeps its feature set focused on observation, recordings, heatmaps, and automated friction detection, rather than branching into surveys or deep funnel analytics, which keeps both the script and the dashboard simple.

Clarity additionally supports custom tags and identifiers through the clarity() function, letting owners label sessions (for example by experiment variant or user segment) so they can be filtered later. These extra clarity() calls are another reason the window.clarity global is such a dependable confirmation that the tool is present.

How to Tell if a Website Uses Microsoft Clarity

Clarity's fingerprints are distinctive and easy to verify across several methods.

View Source. Search the HTML for clarity.ms. The Clarity snippet references www.clarity.ms/tag/ followed by the project ID, and contains a recognizable inline initializer that creates the clarity function and loads the tag. Spotting the clarity.ms/tag/<id> URL is the fastest single confirmation and reveals the project ID.

DevTools Console. Type window.clarity and press enter. If Clarity is active you will get a function back rather than undefined. This confirms the Clarity library loaded and initialized on the page.

DevTools Network panel. Reload with Network open and filter for clarity. You will see the tag fetched from www.clarity.ms/tag/<id> and a stream of data-collection beacons to *.clarity.ms endpoints (such as ingestion subdomains under clarity.ms). These outbound beacons are the runtime proof that session data is being captured and transmitted.

Cookies. Clarity sets two characteristic cookies: _clck (Clarity user ID, persisting a user identifier across sessions) and _clsk (Clarity session cookie, connecting page views within a session). Open DevTools Application > Cookies and look for _clck and _clsk. These two cookie names are among the most reliable Clarity fingerprints, they are nearly unique to the tool.

curl. Fetch the body with curl -s https://example.com | grep -i clarity.ms. For server-rendered snippets this surfaces the clarity.ms/tag/ reference and the project ID. If Clarity is injected through a tag manager it may not appear in raw curl output, so pair it with the Console, Network, and cookie checks.

Wappalyzer and BuiltWith. Both recognize Microsoft Clarity from the clarity.ms script and the _clck/_clsk cookies. They give an instant read, and BuiltWith can show historical adoption. To understand how Clarity fits alongside measurement tools, see our guide on how to find out what analytics a website uses; for the broader stack, how to find out what technology a website uses; and for spotting recorders and heatmaps specifically, how to tell if a website uses Hotjar or a heatmap tool.

A server-side scanner that executes the page and watches clarity.ms traffic will confirm Clarity even when it is gated behind consent or injected via a tag manager, which source-only inspection can miss.

Key Features

• Unlimited session recordings. Capture and replay visits with no sampling cap, free.
• Heatmaps. Click, scroll, and area heatmaps across devices.
• Automated friction insights. Rage clicks, dead clicks, quick backs, excessive scrolling, and script errors detected automatically.
• AI summaries. Plain-language summaries and Q&A over session data.
• Google Analytics integration. Link recordings to GA4 segments for combined quantitative and qualitative analysis.
• Filters and segmentation. Slice recordings by device, browser, country, source, and custom tags.
• Privacy by default. Automatic masking of sensitive content and content-security compliance options.
• No cost, no limits. Free forever with unlimited traffic and projects.

Pros and Cons

Pros

• Completely free with no recording or traffic limits, a major advantage over paid competitors.
• Lightweight script with minimal performance overhead.
• Automated friction detection surfaces problems without manual review.
• Native Google Analytics and Microsoft Advertising integrations.
• Easy setup and privacy-conscious defaults.

Cons

• No built-in surveys or voice-of-customer feedback widgets (unlike Hotjar).
• Less mature for deep, queryable product analytics than enterprise event platforms.
• As a Microsoft product, data flows into Microsoft's ecosystem, which some teams weigh for privacy.
• Fewer advanced funnel and trend tools than some paid alternatives.
• Adds third-party tracking that triggers consent obligations under GDPR/ePrivacy.

Microsoft Clarity vs Alternatives

Clarity's defining trait is that it is free and unlimited, so comparisons usually weigh that against the extra tooling paid platforms provide.

Tool	Price	Recording limits	Surveys	Friction insights	Integrations
Microsoft Clarity	Free	Unlimited	No	Yes (automated)	GA4, MS Advertising
Hotjar	Freemium / paid	Capped by tier	Yes	Yes	Many
Crazy Egg	Paid	Capped by tier	Limited	Partial	Some
FullStory	Enterprise paid	High / custom	No	Yes	Many
Smartlook	Freemium / paid	Capped by tier	No	Yes	Some

The headline comparison is Clarity versus Hotjar. Clarity wins on cost and recording volume, free and unlimited, while Hotjar wins on surveys, feedback widgets, and funnel polish. Because Clarity costs nothing, many teams run it alongside another tool: Clarity for unlimited recordings and automated friction insights, and a second platform for surveys or deeper product analytics. Detecting both on one site is common.

Common Use Cases

• Free behavior analytics for any site: small businesses and side projects that cannot justify paid tools.
• High-traffic recording: sites that need to capture every session without sampling limits.
• Friction diagnosis: quickly surfacing rage clicks and dead clicks that signal broken UI.
• Conversion optimization: watching checkout and sign-up flows to find drop-off points.
• GA4 enrichment: pairing recordings with Google Analytics segments for the "why" behind the numbers.
• Error spotting: catching JavaScript errors that correlate with abandoned sessions.

Frequently Asked Questions

What are the _clck and _clsk cookies?

_clck and _clsk are the two cookies Microsoft Clarity sets. _clck stores a persistent Clarity user identifier across sessions, while _clsk is a session cookie that links page views within a single visit. Finding either in DevTools Application > Cookies is a reliable indicator that Clarity is installed.

How do I confirm Clarity in the browser console?

Type window.clarity and press enter. If Clarity is active, the console returns a function rather than undefined. You can also look in the Network panel for requests to www.clarity.ms/tag/<id> and beacons to *.clarity.ms to confirm data is being sent.

Is Microsoft Clarity really free?

Yes. Clarity is free with no sampling caps, no recording limits, and no charge for traffic or number of projects. Microsoft offers it as part of its broader web and advertising ecosystem rather than as a paid subscription product.

Why is Clarity filed under "ui" rather than analytics?

In StackOptic's taxonomy Clarity is categorized under "ui" because its main purpose is improving the user interface and on-page experience through visual behaviour insight, heatmaps, recordings, and friction detection, rather than counting traffic. Functionally it sits in the same family as other behavior-analytics tools.

Can Clarity be detected with curl?

For server-rendered snippets, yes, run curl -s https://example.com | grep -i clarity.ms to find the clarity.ms/tag/ reference and the project ID. If Clarity is loaded through a tag manager, it may not appear in raw curl output, so combine it with the Console, Network, and cookie checks.

How is Clarity different from Hotjar?

Both offer heatmaps and session recordings, but Clarity is completely free with unlimited recordings, while Hotjar uses freemium pricing with sampling caps and adds surveys and feedback widgets. Clarity emphasizes automated friction insights and a GA4 integration; Hotjar emphasizes voice-of-customer tooling.

What is the Clarity project ID and where do I find it?

The project ID is the alphanumeric string that identifies a Clarity account. It appears in the tag URL as www.clarity.ms/tag/<project-id> in the page source, and it is also embedded in the initialization call. Locating it confirms Clarity is installed and tells you which project the data flows into.

Does Clarity capture sensitive information in recordings?

By default, no. Clarity masks text and input values according to its privacy modes, with the default leaning toward stronger masking so that personal data, passwords, and payment fields are not recorded. Site owners can tune the masking level, but the out-of-the-box behaviour is designed to keep sensitive content out of recordings.

Will Clarity affect my Core Web Vitals?

Clarity is built as a lightweight, asynchronous script specifically to minimize performance impact, so its effect on metrics like Largest Contentful Paint and Cumulative Layout Shift is generally small. As with any third-party tag, loading it efficiently and after the page is interactive keeps the overhead negligible for most sites.

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Want to instantly see whether a site runs Microsoft Clarity, Hotjar, or any other experience-analytics tool? StackOptic detects the full stack from the server side at https://stackoptic.com.