A sub ID is a pass-through value. Whatever the publisher puts on the outgoing link comes back unchanged when the conversion is reported, which lets the publisher attribute it in their own system without depending on anyone else's records.

How it works

Before serving an offer, the publisher appends their identifiers to the tracking URL. The user clicks through and completes the action on the advertiser's side. When the postback fires, those same values are returned, and the publisher matches them against the waiting session to credit the right user.

Click:    https://track.example.com/click?offer=1234&sub1=USER_ID&sub2=PLACEMENT
Postback: https://publisher.example.com/pb?sub1=USER_ID&sub2=PLACEMENT&payout=2.40

Click:    https://track.example.com/click?offer=1234&sub1=USER_ID&sub2=PLACEMENT
Postback: https://publisher.example.com/pb?sub1=USER_ID&sub2=PLACEMENT&payout=2.40

Click:    https://track.example.com/click?offer=1234&sub1=USER_ID&sub2=PLACEMENT
Postback: https://publisher.example.com/pb?sub1=USER_ID&sub2=PLACEMENT&payout=2.40

What to put in them

• A user identifier. The single required value. Without it a conversion cannot be credited to anyone.

• A placement or wall identifier. Lets you compare performance across surfaces in your own reporting.

• A campaign or cohort tag. Useful for tying rewarded revenue back to an acquisition source.

• Nothing personal. Use an internal key, never an email address or anything that identifies a real person in a URL.

Why it matters

Sub IDs are what make a publisher's own reporting possible. Without them you can see that conversions happened but not which placement, cohort, or experiment produced them, which makes optimizing a wall guesswork. They are also the audit trail when a conversion is disputed or reversed.

Sub IDs and reconciliation

Sub IDs are what make disputes resolvable. When an advertiser queries a batch of conversions or a publisher questions a missing payment, the sub ID is the shared key that lets both sides look at the same records. Publishers who pass only a user identifier can confirm who converted but not from where, which turns a five-minute reconciliation into an argument. Passing a placement or campaign value alongside the user ID costs nothing and pays for itself the first time a payment is queried.

Common mistakes to avoid

• Failing to URL-encode the value. An unescaped character truncates the parameter and the conversion arrives unattributable.

• Using a value that changes between sessions. The identifier has to be stable long enough for the conversion to arrive, which may be days.

• Putting personal data in a sub ID. It travels through third-party systems and sits in logs.

• Overwriting a reserved parameter. Networks reserve specific slots for their own use; writing to one silently breaks matching.

• Exceeding the length limit. Values are typically capped around 255 characters and are truncated without warning.