A new user code looks like a steal
A first order discount code can make a grocery app look like the cheapest way to save money on groceries the moment you open it. The welcome banner knocks a chunk off your first basket, and it is tempting to treat that app as the winner and stop comparing. Downloading an app purely for the welcome offer is common enough that most quick commerce apps lean on it as a way to win a first order, knowing that habit often keeps people ordering long after the offer is gone. The honest test of whether a first order code actually helps you save money on groceries is not what it does once, but what the same basket costs on that app once the code is gone and you are back to ordinary pricing like everyone else.
What the discount is actually measured against
A first order code is usually a percentage off or a flat amount off your basket, and both only matter in relation to the starting price. If the app's regular prices run a little higher than a competing app to begin with, a generous looking code can simply bring the total back down to roughly where a cheaper app already sits without a code at all. That is not a trick exactly, it is just how a discount works, but it means the size of the code alone does not tell you whether the app is actually a good deal for your list. A code worth a lot on paper against an expensive starting price can still leave you paying more than a plainly priced app with no code attached.
How to compare it against the regular price
Before you use a first order code, it helps to check the same basket on another app you already use regularly, without any code applied on either side. That gives you a fair read on where the app's normal pricing sits before the welcome offer sweetens it. If the app is already competitive without the code, the discount is a genuine bonus on top. If the app is noticeably pricier to start with, the code is mostly closing a gap it created itself, and you are not saving as much as the welcome banner suggests. Write down what the same list costs with no code anywhere, then look at the discounted total next to it, so the comparison is about the app and not just about the offer.
What happens once the code expires
The real question for anyone trying to save money on groceries over time is what the app charges on your second order and every order after that. A single discounted basket does not change your weekly or monthly spending much on its own. What changes it is which app you keep ordering from once the new user perks are gone, since most shoppers settle into one app out of habit rather than rechecking every time. It is worth checking your usual list again a week or two later, once the code has expired, to see whether the app you tried still holds up against your regular choice on a fair, no code basis. If it does not, there is no reason loyalty to a one-time offer should keep you there.
Stacking a welcome code with other offers
Some apps let a first order code sit alongside a bank offer or a running promotion, which can make the first basket look even cheaper than it really is going forward. How coupon stacking works on grocery apps explains this in more detail, but the short version is that stacked offers are often tied to that specific order and will not repeat. Enjoy the stacked saving on the first basket, but do not plan your ongoing grocery budget around a combination of offers that was never meant to last beyond the welcome period. If a bank offer is what made the first basket cheap rather than the app's own pricing, remember that the same bank offer might apply on a competing app too, which brings you back to comparing the base price rather than crediting the app for a saving it did not really provide.
Cashback and coins are a different kind of discount
A few apps offer a first order perk as cashback or loyalty coins rather than a straight price cut, which changes the comparison again. Cashback vs discounts: which actually saves money on groceries is a useful read here, since coins you redeem later are worth less certainty than a lower price today. A first order cashback offer is fine to collect, but it should not be the reason you judge an app cheaper than one that simply charges less at checkout without asking you to come back and redeem anything.
A simple check before you rely on a first order code
Try the welcome code if it is genuinely there for the taking, but treat it as a one-time event rather than proof of which app is cheapest for you. Comparoo compares live prices across the major grocery apps, so checking your regular list against a few options takes a moment rather than several open tabs. The app with the loudest first order code is not always the one that will save money on groceries once the novelty wears off, and a short comparison a week or two later tells you far more than the welcome banner ever could. Collect the welcome offer, enjoy it, and then let a fair comparison decide where your next order actually goes.