CartHappy - Splits your grocery cart across stores, automatically

Hey PH 👋

I built CartHappy for my mom. She's in metro Detroit, and every week she's doing the same thing — checking flyers, clipping coupons, trying to find which store has eggs cheaper this week. I watched her do this for years and never saw a real fix that didn't ask her to change how she shops.

So we built CartHappy to do that work for her and others (nationwide now), automatically. Connect your store accounts, and it checks 350 million prices a day across 10,000 stores in the US, applies every coupon it finds, and splits your cart to whatever's cheapest that week. It can also learn your regular list from what you buy and build a cart on its own.

The harder problem was everyone building their own version of this locked inside one retailer, but nobody shops in just one store — my mom doesn't, and neither does anyone else. Doing this across retailers meant matching the same product across completely different catalogs, pricing systems, and coupon structures in real time — no shared source of truth to pull from. So the approach had to change: build it as an extension that works horizontally, sitting inside each retailer's site instead of replacing it.

WXYZ Detroit tested it live on TV a few weeks ago — a family synced their purchase history and CartHappy found them $28 in savings, instantly. That's the same thing my mom sees now every week.

It's live across Walmart, Target, Kroger (and its family of companies), and Safeway — we're working on adding more. Would love feedback from this community, especially on what would make it more useful week to week.

Thank you!
John

honestly love the cart splitting idea, super smart. one thing i'd want though is some kind of delivery coordination, like if the cheapest cart ends up split across three different stores, it would be nice if the extension could either schedule pickups or show me a single delivery option that consolidates everything so i'm not driving all over town on a tuesday evening

honestly this looks super useful, the cross-store cart split is clever. one thing i'd love though is a price drop alert for items on my regular list, like if the chicken i buy every week goes on sale at aldi, just ping me so i can wait or stock up

Tried it on my usual Walmart run and it actually flagged a cheaper version of my coffee at Kroger, plus stacked a coupon I never would have found. The browser extension feels invisible in a good way.

One thing I'd love to see is a shared family list mode, where my partner and I can both add items in real time and CartHappy splits the cart between stores based on whoever is shopping that day. That would make the auto-cart feature way more useful for households that don't always shop together.

I dig how it doesn't just show you the prices elsewhere, but creates the basket for you w/ item already added