Addy 
Addly 
Goalify 
Monet 
Reviso 
Key takeaways
- A checkout-initiation offer has to be skippable in one click and fast. If it adds a second of delay, you are taxing the people who were going to pay.
- The offer must be cart-aware. A generic "10% off" at checkout start is a coupon interstitial, not an upsell.
- Never block the checkout button behind a timer or a required choice. That is a dark pattern and a conversion leak.
- If they already declined the same SKU in the cart or on add-to-cart, do not ask again here.
The click on checkout is the most expensive click on the site. Intercepting it is allowed only if you are almost invisible: one relevant product, one add, one obvious skip, no delay.
If any of those fail, you are standing in front of the till.
Instant or not at all
When checkout is clicked, the overlay must already know what to show. Fetching an offer at click-time is how you introduce a spinner between "I want to pay" and paying. Prefetch on cart open. Cache it. Fail open: if the offer is missing, go to checkout.
What to offer
Something small, complementary, and easy to evaluate without a PDP: a matching accessory, protection, a consumable refill. Not a new hero product. Not a subscription pitch that needs a paragraph.
If the cart is already above your free-shipping threshold, do not offer more cheap items "to help". They are trying to leave.
Skip must be the easy action
A clear "No thanks, continue to checkout" — not a tiny X, not a 5-second lock, not a second overlay. The people who skip were going to pay. Let them.
Do not repeat a no
If this SKU was already shown on add-to-cart or in the drawer, checkout initiation is not a new conversation. Frequency cap across triggers. One offer per session still applies here — especially here.
Done well, this is a quiet extra few points of attach rate from people who were already sold. Done poorly, it is the reason your checkout initiation rate dropped last Tuesday and nobody knew why.
Frequently asked questions
Will this slow down checkout?
It will if the popup waits on a slow network request. Prefetch the offer when the cart opens so checkout click can paint immediately. If you cannot be instant, do not intercept checkout.
Is this allowed on Shopify?
You cannot inject into Shopify checkout itself. You can intercept the click that *starts* checkout, on your storefront, then send them on. Do not try to modify checkout.liquid in 2026.
Should I offer a discount to stop them leaving?
Not at this moment. They have clicked pay. A sudden discount teaches them to click checkout to unlock a deal. Offer a complementary SKU or nothing.
What if they have a discount code already?
Still fine to offer a product. Do not stack a second code. The overlay is for a SKU, not for a coupon war.
