Click ID
A click ID is a unique alphanumeric code that an ad platform adds to a destination URL each time someone clicks an ad. It identifies that exact click so the platform can later match it to a conversion. Unlike a UTM tag, a click ID is machine-readable and assigned automatically, not written by a marketer.
Why Click IDs Matter
Click IDs connect a single ad click to what happens after it. When a user clicks a Google or Meta ad, the platform appends a click ID to the landing page URL. If that user buys something hours or days later, the stored click ID is sent back to the platform. The platform then credits the exact ad, keyword, audience, and placement that drove the sale.
This precision powers automated bidding. Google’s Smart Bidding and Meta’s Advantage+ rely on click IDs to learn which clicks convert, then shift budget toward them. Without click IDs, conversion data stays vague and platforms optimize blindly. Click IDs also enable offline conversion import, where a CRM sale recorded weeks later is matched back to the original click.
Common Click IDs by Platform
Each major ad platform uses its own click ID parameter:
- GCLID (Google Click Identifier): added by Google Ads auto-tagging.
- GBRAID and WBRAID: Google’s privacy-safe click IDs introduced after Apple’s iOS 14 changes, used for app and web conversions.
- DCLID: Google’s click ID for Display and YouTube campaigns.
- FBCLID: Meta’s click ID for Facebook and Instagram ads.
- MSCLKID: Microsoft Advertising (Bing Ads).
- TTCLID: TikTok Ads.
- LI_FAT_ID: LinkedIn Ads.
- EPIK: Pinterest Ads.
A tagged Google Ads URL looks like this:
https://linkutm.com/?gclid=Cj0KCQjw_abc123XyZ
How a Click ID Works
The flow runs in four steps:
- A user clicks an ad. The platform appends its click ID to the landing page URL automatically.
- The website stores the click ID, usually in a first-party cookie or hidden form field.
- The user converts. The click ID is captured with the conversion event.
- The platform receives the click ID through its pixel, API, or offline import, then matches the conversion to the original click.
Auto-tagging must be enabled for this to work. In Google Ads, the gclid is added only when auto-tagging is on, which is the default setting.
Click ID vs UTM
A click ID and a UTM serve different systems. A UTM is human-readable text you write yourself, like utm_source=facebook&utm_medium=cpc. Analytics tools such as GA4 read UTMs to label traffic. A click ID is an opaque code the ad platform generates and reads, used to optimize bids and import conversions.
| Click ID | UTM | |
|---|---|---|
| Created by | Ad platform, automatically | Marketer, manually |
| Read by | The ad platform | GA4 and analytics tools |
| Readable | No (random string) | Yes (plain words) |
| Purpose | Match conversions to a click | Label traffic source and campaign |
The two work together. Auto-tagging handles gclid for Google Ads reporting, while UTMs label the same visit inside GA4. For channels without auto-tagging, you still need UTM parameters to track campaigns. Click IDs power the ad platform’s view; UTMs power your analytics view. For more on capturing clicks across both, see click tracking.
How to Check a Click ID
Click one of your own ads and inspect the URL in the address bar. Look for a parameter like gclid=, fbclid=, or msclkid=. If it is missing, auto-tagging is likely turned off. In Google Ads, confirm auto-tagging under Account Settings. A URL parser can split the query string and show each click ID and UTM side by side.
Frequently Asked Questions
What is a click ID?
A click ID is a unique code an ad platform attaches to a URL when someone clicks an ad. It tracks that single click so the platform can match it to a later conversion. Each platform uses its own, such as gclid for Google and fbclid for Meta.
What is the difference between a click ID and a UTM?
A click ID is generated automatically by the ad platform and read by that platform to optimize bids. A UTM is written manually and read by analytics tools like GA4 to label traffic. Click IDs are random strings; UTMs use plain, readable words.
What is a GCLID?
GCLID stands for Google Click Identifier. Google Ads adds it to your landing page URL through auto-tagging. It lets Google match conversions, including offline sales imported within 90 days, back to the exact ad click.
Are click IDs personal data?
Click IDs do not directly identify a person. They reference an ad click, not a name or email. Ad platforms use them to link conversions to campaigns, not to expose individual user identities.
Do I need both a click ID and a UTM?
Often yes. The click ID feeds the ad platform’s conversion and bidding system, while the UTM feeds your analytics. Using both gives you accurate reporting in Google Ads and in GA4 at the same time.
To tag campaigns that auto-tagging does not cover, build clean links with the free UTM builder at linkutm.