GCLID, FBCLID and MSCLKID: A Practical Guide to Ad Click IDs

What these parameters tell you

Advertising systems can attach identifiers to landing-page URLs. Google Ads commonly uses gclid when auto-tagging is enabled; Microsoft Advertising uses msclkid; Meta links may include fbclid. These parameters are not the same as campaign labels and are not interchangeable between platforms.

Click IDs are only useful when a compatible campaign and consent setup exists. Their presence does not prove a purchase or a qualified lead, and their absence does not automatically mean traffic was not paid.

Click IDs versus UTM parameters

• UTM parameters are human-readable traffic labels such as utm_source, utm_medium and utm_campaign.
• A click ID is a platform-generated identifier that may help that platform associate an event with an eligible ad interaction.
• Store the identifiers separately. Do not rename fbclid to gclid or put an entire query string into a single generic field.
• Validate length and characters before persisting untrusted URL parameters; keep only what is necessary for your attribution requirements.

How to preserve a click through form submission

Read relevant landing-page parameters and carry them alongside a form submission, using your permitted tracking and consent policy. When a user passes through several pages before submitting, design attribution persistence explicitly rather than assuming the original query string will survive.

A reliable lead record should retain its own submission ID and creation time. Click identifiers are additional context, not replacements for a lead ID. When applicable, link later recorded outcomes to the correct submission rather than inferring sales from clicks alone.

// Read only identifiers present on the landing-page URL.
const params = new URLSearchParams(window.location.search);
const keys = ['gclid', 'fbclid', 'msclkid'];
const clickIds = Object.fromEntries(
  keys.flatMap((key) => {
    const value = params.get(key);
    return value ? [[key, value]] : [];
  }),
);
// Persist or submit only as permitted by your consent policy.

Avoid mixing storage with conversion reporting

Preserving a parameter on a lead is not the same as sending a conversion to Google Ads, Meta, or Microsoft. Server-side feedback typically needs additional provider configuration, access, valid identifiers, privacy controls, and a qualifying event.

Panther Hook preserves supported attribution fields and offers optional performance and feedback workflows on eligible plans. Make sure your campaign expectations match the configured destinations and any platform requirements.