Everything you'd reasonably want to know about CartChkr — install, scanning, the Move feature, pricing, privacy, and what to do when Coles plays up.
CartChkr is a free Chrome extension for Australian grocery shoppers. You load up your trolley at Woolies or Coles as normal, click the CartChkr button, and it compares every item against the same product at the other store. Anything cheaper at the other store gets a one-click Move button that switches the item across for you.
It works in both directions — start at Woolies and compare to Coles, or start at Coles and compare to Woolies.
Chrome and any Chromium-based browser — Microsoft Edge, Brave, Arc, Opera, Vivaldi. If you can install extensions from the Chrome Web Store, CartChkr works.
It does not work on Safari, Firefox, or mobile browsers (Chrome for iOS/Android don't support extensions). Firefox is on the roadmap; Safari and mobile are further out.
No account, no email signup. CartChkr uses your existing Woolworths and Coles logins — it reads the prices your browser already has access to and never asks for your credentials.
Open the CartChkr Chrome Web Store page and click Add to Chrome. After installing, pin CartChkr to your toolbar (click the puzzle-piece icon, then the pin next to CartChkr) so it's easy to find. Open Woolies or Coles, click the CartChkr icon, and the sidepanel will appear.
To compare prices, CartChkr needs to read your trolley contents and look up the matching items at the other store. That's all the permission is for. It can't see anything on any other site, it never reads your passwords or payment details, and it doesn't send your cart anywhere — see the privacy section.
Sign into both stores in separate tabs and load up your trolley at one of them. Open the CartChkr sidepanel, then click the W (Scan) button if your trolley is at Woolies, or the C (Scan) button if it's at Coles. CartChkr fetches every item, finds the matching product at the other store, and shows you a side-by-side comparison.
Typical scan takes 5-15 seconds depending on cart size. You'll see a progress bar.
Three common reasons:
If you spot a "no match" that you think IS available, click the 👎 on the match — we use those signals to improve scoring.
Click Move and CartChkr adds the matching product to your trolley at the cheaper store, then removes the item from your original cart. If anything fails partway through, it rolls back automatically so you don't end up with an item missing or duplicated.
Everything happens inside your own browser session using your existing logins — no separate checkout, no payment to us beyond the one-time licence.
If a Move fails for any reason, CartChkr rolls it back automatically — the item goes back to its original cart. For a successful Move you've changed your mind about: just remove the item from the new cart and re-add it at the original store. We'd love to add a one-click undo down the track but it's not in v1.
Not yet. CartChkr currently compares Woolworths and Coles — the two stores with comparable online trolley experiences. ALDI doesn't offer the same online cart functionality, and IGA / Costco vary store by store. We're aiming at New Zealand next (Pak'nSave + Woolworths NZ), then revisiting AU options.
No — CartChkr is a Chrome desktop extension. Chrome on iOS and Android doesn't support extensions, and Safari is a separate platform. Mobile support is on the long-term roadmap.
Yes. As long as you're signed in at Woolworths with your Everyday Rewards account (and Coles with your Flybuys account), CartChkr sees the prices you actually pay — member specials and reward pricing are baked into the comparison.
Scanning is free, forever. Add items to your Woolies or Coles cart, hit Scan, see the comparison — no payment.
The Move feature (one-click switch to the cheaper store) requires a one-time licence:
Most users save $15-$25 per shop, so the licence pays for itself the first time you use it.
Click any Move button in the sidepanel. You'll see a plan picker — choose Founding or Lifetime — and complete checkout through ExtensionPay (which handles billing via Stripe). Your plan activates the moment payment succeeds.
Yes — email [email protected] within 14 days of payment and we'll refund you, no questions asked. Refunds process through Stripe and usually land in your account within 5-10 business days.
No. Your plan is tied to your ExtensionPay account, not your browser — clearing data doesn't lose your licence. Open CartChkr and the licence check runs fresh on each open. If it stays locked, email [email protected] with your purchase confirmation from ExtensionPay/Stripe and we'll restore it manually within a day.
Email [email protected] with the purchase confirmation you got from ExtensionPay/Stripe and we'll cancel it from our side. Access continues until the end of the current billing period either way — no charge after that, no fuss.
If you have trouble, email [email protected] and we'll sort it out.
Close the CartChkr sidepanel completely (click the toolbar icon to dismiss), then reopen it. The licence check runs fresh on every open and should activate immediately.
If it's still locked after reopening, email [email protected] with your payment confirmation email and we'll manually verify and activate your account.
Your cart contents stay in your browser. CartChkr does not send your shopping data to any server we control. It doesn't store what you buy, when you shop, or what your trolley looks like.
The only external service it touches is ExtensionPay (via Stripe) for licence verification, if you've bought a plan. ExtensionPay sees your email and payment status — nothing about your shopping. See our Privacy Policy for the full breakdown.
No. CartChkr never reads, stores, or transmits your passwords or auth tokens. It uses the active session your browser already has with each store — exactly the same session you use to shop normally.
There's no telemetry to opt out of — we don't collect any. If you've bought a plan and want your ExtensionPay account data deleted, email [email protected] and we'll process the deletion through ExtensionPay's customer-data flow within 30 days.
No. CartChkr is an independent tool built by an Australian developer. It's not affiliated with, endorsed by, or sponsored by Woolworths Group Limited or Coles Group Limited. We just shop there like everyone else and got tired of comparing prices by hand.
You've hit Coles' bot-detection (Imperva). It's not CartChkr being blocked specifically — Coles runs a security check that occasionally challenges automated traffic, including the kind of programmatic browsing the extension does. Fix:
If it keeps happening every shop: sign out and back in at coles.com.au — that usually clears any stuck session state. We're working on a fully automated workaround but for now this manual nudge is the most reliable fix.
Woolworths sessions last about 24 hours. If yours has expired, sign back in at woolworths.com.au, then retry the scan. CartChkr will pick up the fresh session automatically.
Click the 👎 next to the bad match in the sidepanel. CartChkr will block that pairing for future scans and we use those signals to improve the matcher. You can also click 👍 on a correct match to lock it in — saved matches persist across scans.
Common causes of bad matches: branded vs unbranded confusion (e.g. Cadbury vs Coles-brand chocolate), size variants (250g vs 500g), and fresh produce naming differences. We enforce brand-match for third-party brands but the fresh-produce side is still imperfect.
Most often this is the same Coles bot-block issue — the Move couldn't complete because Coles was rate-limiting. Follow the steps in the Coles loading question, then click Move again.
If it's not bot-block: CartChkr has a name-based fallback for fresh produce that sometimes needs a second pass. Clicking Move a second time will often succeed.
If it still fails after two tries, click Report Issue in the sidepanel footer — diagnostic logs are attached automatically and we'll investigate.
If literally every item shows no match, the target store is bot-blocking your whole session. Manually visit coles.com.au or woolworths.com.au, complete any "Verify you're human" check that appears, then come back and re-scan.
Use the Report Issue button in the CartChkr sidepanel footer. You'll get three options: open Gmail in browser, open your default mail app, or copy the diagnostic logs to clipboard. Whichever you pick, the logs (cart state, last few errors, extension version) are attached automatically — you don't need to write anything technical, just describe what you were trying to do.
Open the CartChkr sidepanel → click the Saved tab at the top. You'll see every match you've thumbs-upped (saved) and thumbs-downed (rejected). From there you can unpin a saved match or unblock a rejected one.
Woolies and Coles run weekly specials that rotate constantly — hundreds of items change price every week depending on supplier deals, promotional calendars, and competitive pricing. There's no consistent pattern; the cheaper store genuinely changes week to week for most households.
That's exactly why CartChkr exists. Checking by hand takes 20+ minutes. CartChkr does it in 10 seconds.
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