Promo Code Generator

A promo code generator creates the codes that customers type at checkout to get a discount, free shipping or a gift. Good codes are easy to read and type, different from each other, and hard to guess. This page makes them in your browser with the Web Crypto API and shows how hard they are to guess.

Each character is chosen with the browser’s cryptographically secure random generator, using rejection sampling so that every character is equally likely. Letters and digits come from an alphabet without look-alikes: the letters I and O and the digits 0 and 1 are left out. With uppercase letters and numbers that leaves exactly 32 symbols, which is 5 bits per character. Special characters are optional, and many checkouts reject them.

Within one batch, yes: every code is checked against the others and duplicates are discarded, so you always get exactly the number you ask for. Different batches are independent, so compare new codes with the ones you issued earlier. The old version of this page generated every code independently, and a batch of 1,000 four-character codes contained a duplicate roughly four times in ten.

Length is about guessing, not secrecy. The page shows the chance that one random guess hits one of your codes. With 8 characters from 32 symbols there are about 1.1 trillion codes, so 1,000 live codes would be hit by a guess about once in 1.1 billion tries. 6 characters gives about a billion codes and is fine for a short flash sale. Whatever the length, limit failed attempts at checkout and validate codes on your server.

Most shops treat codes as case-insensitive, so a code with both upper and lower case letters could clash with another code that differs only in case. Choose one letter case instead. Look-alikes such as 0 and O, or 1 and I, cause failed redemptions when customers type a code from a screenshot or a printed card.

It removes the vowels A, E, I, O and U from the letters, so random codes cannot spell words, which also means they cannot accidentally spell something rude. It reduces the number of possible codes, and the guess odds shown take that into account.

It compares a code with your current settings (prefix, suffix, grouping, length and characters) and applies the rules most checkouts use: no spaces, no unusual characters, a sensible length and no easily misread characters. It points out a probable typo, such as a zero where the generator would use the letter O. It cannot tell whether a code has been issued or is still valid, because that depends on your shop.

No. Codes are generated in your browser, the page’s content security policy blocks outgoing network requests, and nothing is saved except your language choice. Earlier versions of this page loaded a script from an outside server, ignored the prefix, suffix and format in bulk mode, and rejected some of the page’s own codes in the validator.