What Are Click IDs and Sub IDs?

What are click IDs and sub IDs?

A click ID is a unique value that an ad platform or tracker creates for every single click, so a later conversion can be matched to exactly that click. A sub ID is a value you add to a link yourself, such as the name of a page, placement, or campaign, and it is returned to you in reports and postbacks so you can see where results came from. In short: the platform generates the click ID, and you choose the sub IDs.

Click ID vs sub ID at a glance

How click IDs and sub IDs travel in URLs

Both ride along as query parameters. Platforms use macros, placeholders in curly brackets, that are replaced with real values at the moment of the click or the conversion.

1. The publisher adds sub IDs to its link. A rewards site might open an offerwall with ?user_id=4821&sub1=homepage&sub2=summer_promo.
2. The platform records the click. It stores the sub IDs and creates a click ID, then sends the user on to the advertiser’s tracking link, for example https://track.example.com/start?cid={click_id}, with the macro filled in.
3. The advertiser keeps the click ID. Its server saves the value with the new user, ready for later.
4. The conversion is reported. The advertiser’s server calls the platform’s postback URL with click_id= and the stored value.
5. The sub IDs come back. The platform finds the click and its saved sub IDs, and fills them into its postback to the publisher, for example &src={sub1}, so the publisher sees that this reward came from the homepage summer promotion.

This round trip is the heart of server-to-server tracking. Which macros a postback can carry, and how statuses work, is covered in What is a postback URL?

What click IDs and sub IDs are used for

• Attribution. The click ID ties a sign-up on Friday to the click on Tuesday, without cookies.
• Source reporting. Sub IDs let you split earnings or costs by site, page, placement, campaign, or creative, so you know what to keep and what to cut.
• De-duplication. One click ID can only convert once for each event. A second report of the same event for the same click ID is a duplicate, not a new sale.
• Fraud checks. The click ID lets you compare click time with conversion time. Conversions that arrive seconds after a click, or long after any normal user would act, deserve a closer look.
• Support. When a user says a reward is missing, the click ID or the sub IDs let both sides find the exact click in their logs.

A simple sub ID plan

Decide once what each slot means and stick to it, or your reports turn into a mix of values that cannot be compared. For example:

Use short, lowercase values made of letters, numbers, and underscores. They survive every system and are easy to group. If you already tag links for your own analytics, UTM parameters do a similar job inside your own analytics tool, while sub IDs do it inside the partner’s reports and postbacks.

Common click ID and sub ID mistakes

• Personal data in sub IDs. Emails, names, or phone numbers in a URL end up in server logs, analytics tools, and partners’ databases. Use an internal ID that only you can look up instead.
• Overwriting the click ID. A redirect, a second tracker, or a page that generates a new value on every load can replace the stored click ID. Save it once, at the first visit, and do not let later pages change it.
• Reusing a slot for two meanings. If sub2 is a placement this month and a country next month, old and new reports no longer match.
• Not URL-encoding values. A space, &, #, or + in a value can cut it short or create a new parameter. Encode every value you put into a URL.
• Macros that were never replaced. If you see {click_id} literally in your logs, the macro name is wrong for that platform.
• Crediting users by a sub ID. Anyone can edit a value in a link. Credit rewards only by a user ID that is protected, for example with a signed link.
• Ignoring limits. Platforms cap the length and allowed characters of sub IDs. A value that breaks the rules may be cut or dropped without warning.

Frequently asked questions