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Numbers

Custom Format Code Generator

Used by developers, writers, and creators worldwide.

The custom format code generator lets you build random codes in any pattern you define — paste in a structure like AAA-#### or PROMO-****-**** and get a clean batch in seconds. Type # for a digit, A for a letter, or * for either; everything else passes through as a literal, so dashes, dots, and fixed prefixes stay exactly where you put them. You control three inputs: the pattern, how many codes to produce (up to 100 per run), and whether letters come out uppercase, lowercase, or mixed. Uppercase is easier to read aloud from a printed receipt; lowercase fits cleaner in URLs. A four-letter, four-digit pattern like AAAA-#### already yields over 45 million combinations, which covers most voucher and serial-number campaigns without a script.

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How to use

  1. Choose your options above
  2. Click Generate
  3. Copy your result

Detailed instructions

  1. Type your desired pattern into the Pattern field using # for digits, A for letters, and * for either — keep any separators like dashes or slashes exactly as you want them to appear.
  2. Set the count field to the number of codes you need, up to 100 per run.
  3. Choose Uppercase, Lowercase, or Mixed from the Letter Case dropdown to control how letter placeholders are rendered.
  4. Click Generate to produce the full list of codes instantly.
  5. Select all generated codes, copy them, and paste directly into your spreadsheet, email tool, or database.

Use Cases

  • •Generating 100 uppercase discount codes like SAVE-A4X9 for a Shopify flash sale
  • •Producing booking references in format BK-AAA-#### for an event ticketing platform
  • •Creating license keys in AAAA-####-AAAA-#### format for a software product launch
  • •Seeding a Postgres staging database with realistic mock user IDs in a fixed schema
  • •Building alphanumeric referral codes in mixed case for a WooCommerce affiliate campaign

Tips

  • →Prefix your codes with a campaign tag like SUMMER-*** so you can identify the source without a database lookup.
  • →Avoid patterns shorter than six placeholders for any public-facing code — short patterns are easy to guess by brute force.
  • →Use the * wildcard instead of all A or all # when you want codes that feel more random and less like a simple number sequence.
  • →For phone-number-shaped test data, use a pattern like (###) ###-#### — the punctuation is preserved automatically without any extra steps.
  • →When creating codes for printed materials, set Letter Case to Uppercase and avoid the * wildcard to prevent visually confusing characters like 0 vs O appearing together.
  • →Generate a batch of 100, paste into Excel or Google Sheets, and use the COUNTIF function on the column to catch any duplicates before distributing.

FAQ

how do I create a voucher code with a fixed prefix like PROMO-

Type the prefix directly into the pattern field, for example PROMO-####-AAAA. Any character that isn't #, A, or * is treated as a literal and appears in every code. Set letter case to Uppercase if you want the letter segments capitalised.

what's the difference between # A and * in the pattern

# outputs a random digit (0–9), A outputs a random letter, and * outputs either with equal probability. Use * when you want maximum entropy at a position and don't care about character type — useful for short codes where every extra combination counts.

are the generated codes guaranteed unique

Uniqueness is not enforced, so duplicates are theoretically possible. For high-stakes uses like paid vouchers, paste the batch into a spreadsheet and run a duplicate check before distributing. Longer patterns with more placeholders make collisions statistically rare.