Definition
A cookie window, also called an attribution window or lookback window, is the number of days a tracking cookie remains active after a visitor clicks an affiliate link. If the visitor converts within that window, the affiliate gets credit. If the cookie expires before the conversion, the affiliate earns nothing for that referral. Most programs set cookie windows between 30 and 90 days.
How it works
A visitor clicks an affiliate's link on March 1st. Your tracking system drops a first-party cookie on that visitor's browser with an expiration date based on your cookie window. If you have set a 30-day window, the cookie expires on March 31st. If the visitor comes back on March 20th and buys, the cookie is still valid, the system reads the affiliate ID from it, and the affiliate is credited. If the visitor waits until April 5th, the cookie has expired and the conversion is unattributed.
Some programs use different windows for different actions. You might set a 90-day window for first-time purchases but a 7-day window for upsells. The right duration depends on your typical sales cycle. A $10 impulse buy does not need 90 days. A $10,000 enterprise deal might need longer.
Why it matters
Your cookie window directly affects affiliate recruitment and retention. Longer windows are more attractive to affiliates because they protect the affiliate's investment in driving awareness even if the customer takes weeks to decide. Shorter windows reduce your risk of paying for conversions that were influenced by other channels after the initial click.
The tension is real. Set it too short and affiliates feel cheated when their referrals convert a day after expiry. Set it too long and you might be crediting affiliates for organic customers who would have converted anyway. Look at your average time from first visit to purchase and add a reasonable buffer.
Trcker tip
Trcker lets you configure different cookie windows per program and per partner tier, giving you the flexibility to reward high-value affiliates with longer attribution periods.