Find duplicate barcodes in Shopify
Why Shopify lets two variants share a barcode, what that does at the till, and how to find and clear every duplicate in your catalog.
Coming soon to the Shopify App Store
Markio — Barcode Labels & SKU Generator
Find duplicate and invalid barcodes, fix them safely, and print labels wherever you work — at your desk, at the shelf, or on the till.
Why it exists
A scanner that rings up the wrong product is a data problem, not a printer problem
Most barcode apps start at the printer. Markio starts one step earlier, in the catalog: the same code on two variants, a check digit that never validated, a code with a space in it that no scanner will read, a whole vendor with no codes at all. You cannot print your way out of any of those.
So Markio reads your catalog, tells you exactly what is wrong with the codes in it, and lets you repair them in bulk — showing every change before it is applied, and keeping an undo afterwards. Then it prints, at the exact size of the stock in your printer.
Features
From a broken catalog to a printed shelf
Catalog audit
Fourteen kinds of barcode problem in one report — duplicates, invalid check digits, wrong lengths, unscannable characters, missing codes — ranked by whether they cost you money at the till today. See how duplicates are found.
Bulk fixes with an undo
Preview every proposed change before and after, apply it to your catalog, and take the whole batch back if it was wrong. The undo re-reads the live value first, so it never overwrites something you changed since.
Barcode and SKU generation
Issue codes to the variants that have none, with your own numbering rules, prefixes and patterns — or with your GS1 company prefix, where you own one. Free, with no limit on how many. How the SKU rules work.
A label editor with real sizes
Design what goes on the label and where: product fields, metafields, market prices, images, shapes and conditions. Any size from a quarter inch to twelve, plus Avery sheets and custom grids — including finishing a part-used sheet.
Print where you actually are
Size-matched PDFs from the admin, direct ZPL to a Zebra, or straight from Shopify POS at the counter. Printing from POS.
Print a delivery that just arrived
Paste the CSV of what actually turned up — from your purchase-order app, or a saved Stocky export — match it to your catalog by SKU or barcode, and every received unit gets a label.
Scan verification
Scan a printed code and see which variant it really identifies. That is the difference between believing a label is right and knowing it. When a barcode will not scan.
History, roles and an audit log
Reprint any job exactly as it printed, print a few more of one line, filter by who printed it, and restrict an operator to their own location.
Pricing
Two plans, and printing is unlimited on both
Markio never charges per label. The free plan is a working barcode app, not a demo — the paid plan is for stores that change their catalog in bulk and print away from the desk.
Free
$0 / month
- Barcode and SKU generation, no limit on how many
- Every supported format, including GS1-128 and Data Matrix
- The label template editor
- Custom label sizes, Avery sheets and custom grids
- Unlimited PDF printing, single and bulk
- Multilingual labels
- The whole catalog audit report, read-only
- Export your codes to a spreadsheet
- One saved printer profile, reprints from the last 7 days
Pro
$9.99 / month
- Everything in Free
- Bulk barcode fixes with a before-and-after preview and an undo
- Scheduled audits and email alerts
- Printing from Shopify POS
- Printing from a receiving CSV
- Scan verification
- Extra codes a product also answers to
- Direct Zebra (ZPL) printing
- Saved print jobs, full history, roles and an audit log
- Per-location restrictions
$99.90 a year if you pay annually — two months off. Billed by Shopify through your existing Shopify invoice; we never see a card.
Said up front
Three things about the platform, before you install
These are not our choices — they are limits of the browser and of Shopify's API. You will meet all three, so they belong here rather than in a support ticket.
Printing opens a separate browser tab. Chrome closed web pages' access to devices on your local network, and an app embedded in the Shopify admin can no longer reach a printer service running on your own computer. Markio prints from a tab on its own address instead. Allow pop-ups for the Shopify admin, or that tab will never appear.
Markio does not read Shopify purchase orders. Shopify's Admin API does not expose them. Markio starts from a CSV of what actually arrived instead. It prints the labels; it does not replace the system where you create and receive purchase orders.
There is no printing from an order, and no customer data. Markio does not request protected customer data, so it never asks Shopify for orders or for anything about a buyer. Nothing about your customers is stored — and in exchange there is no "print labels for this order" button. Print from the product list, a collection, a scan, or a delivery file.
Guides
Common barcode problems, answered
A barcode that will not scan
Check digits, wrong lengths, stray spaces, and bars printed too narrow for your scanner — the five causes, in the order worth checking.
Generate SKUs in bulk
Numbering rules, prefixes and pattern tokens, and how to give every variant a code without giving two of them the same one.
Print labels from Shopify POS
Printing at the counter from a product, a scan or the smart grid — and what a tablet can and cannot send to a printer.
Support
Questions about Markio?
Browse the Markio help center for setup, the template editor, the catalog audit, printers and troubleshooting. Or email us at support@veltriolabs.com — we typically reply within one business day. You can also visit our support page for more ways to get help.
Our privacy policy and terms of service for this app are published in full.