Codes FAQ and limits
The facts worth knowing before you generate at scale: how codes behave at checkout, the characters they use, the store-wide code ceiling, and how big batches reach Shopify.
This page collects the details that matter once you start generating codes in volume. Most of them come from how Shopify itself handles discount codes, so they apply no matter which app created the code.
How codes behave at checkout
Are codes case-sensitive?
No. Shopify treats discount codes as case-insensitive at checkout, so SUMMER20, summer20, and Summer20 are the same code. You can share a code in whatever case reads best without worrying that a shopper will type it wrong.
What characters do generated codes use?
Generated codes deliberately leave out characters that are easy to confuse: there is no zero and no letter O, no digit one, and no letter I or L. That makes a code safe to read aloud, print on packaging, or type from a photo without a shopper mixing up look-alike characters. Any prefix you add is used exactly as you type it.
The store-wide code limit
Shopify allows 20 million codes per store, shared by everything
A Shopify store can hold up to 20 million discount codes in total. That ceiling is shared by every app that creates codes and by Shopify’s own discounts, not per app and not per campaign. If your store is near the ceiling, new code creation can fail until unused codes are removed. Generating millions of codes you never send out uses up that shared budget, so generate the batches you will actually use.
For most stores this is not a concern. It matters mainly if you run very large drops or have several apps all minting codes. If you plan campaigns in the hundreds of thousands or millions, keep an eye on how many codes already exist across your store.
The Codes page shows a Store code capacity meter so you never hit the ceiling by surprise. It warns you once your store passes 80 percent of the 20 million limit, and turns critical at 95 percent, where new code creation and Klaviyo top-ups pause until you free space. To reclaim room, the "Clean up unused codes" tool removes never-used codes from ended or archived campaigns. You review the exact list first and confirm before anything is deleted; live campaigns and any redeemed code are never touched. See Store code limit and cleanup for the full walkthrough.
How big batches reach Shopify
When you generate a batch, Stackable creates the codes and sends them to Shopify in the background, 250 at a time. You do not have to wait on the page. A small batch is ready almost immediately; a very large batch keeps processing after you leave, because Shopify accepts codes in chunks rather than all at once.
Large batches take time
A batch of tens or hundreds of thousands of codes is not instant. Shopify processes the chunks over time. If you are preparing for a big launch, generate the batch ahead of the drop rather than at the moment you need the codes live.
What do the batch statuses mean?
Each batch carries a status while it imports. It shows Syncing while codes are being pushed to Shopify 250 at a time, Verified once every code has been confirmed imported, and Needs attention if any code was rejected (for example a rare duplicate that already exists on another discount). A large batch can stay at Syncing for a while, which is normal.
Can codes expire?
Yes. You can set an expiry date when you generate a batch, and every code in that batch stops working after that day. The expiry is fixed for the batch at generation and offers two enforcement modes. Usage limits stay on the campaign and apply to every code. See How code expiry works for the full detail.
Common questions
Why is the Generate codes button disabled?
The campaign is not published yet. Codes attach to a live discount, so publish the campaign first, then generate. A reminder banner appears on the card until it is published.
Can one code cover product, order, and shipping at once?
Yes. In the builder, the "Which discount types this code covers" setting lets one code extend beyond its campaign’s own type to also cover order and shipping discounts.
If I set Total uses to 1, is that one use for the whole batch?
No. The limit applies to each code individually, so every code in the batch can be redeemed once. That is how you hand out single-use codes to a list of recipients.
Can I get my codes back out as a file?
Yes. Every batch has an Export link that downloads the codes as a CSV, and you can re-export the same batch later. See Share and distribute codes.
What happens to codes if I remove the campaign?
Codes and any auto-apply links stop working when the campaign ends or is removed, because they redeem against that campaign’s live discount. Archive keeps the campaign and its history and is reversible; delete is permanent.