Random Code Generator Tutorial: Custom Character Sets for Bulk Codes

2026-09-20 · Card Tools

One-time codes such as redemption codes, coupon codes and activation codes need to look random and follow no guessable pattern. The Random Code Generator lets you define the character set, the length of each code and the batch size, so you can generate at whatever security level you need: uppercase letters and digits only, stripped of the easily confused characters (like 0/O and 1/I), or with special symbols mixed in.

1. How to design your character set

• Default A-Z + 0-9: a good fit for most redemption-code scenarios;
• Drop the easily confused characters: removing 0, O, 1, I and l keeps the codes readable even when printed on paper cards;
• Digits only: suits SMS-style verification codes, and lets you use a shorter length;
• Add special symbols: raises the cost of brute-force guessing and suits higher-value codes.

2. How to choose the length

The strength of a code is directly tied to its length and the size of the character set. As a rough rule of thumb, with 36 characters (uppercase letters plus digits) an 8-character code offers around 2.8 trillion combinations, which is plenty for small campaigns; for high-value or high-volume codes, go with 12 to 16 characters.

3. How to use it

1. Type the characters to draw from into the Character Set field (defaults to A-Z and 0-9; add or remove characters as you like);
2. Set the Code Length (e.g. 16) and the Quantity to generate (e.g. 100);
3. Click Generate and the random codes appear in the output box;
4. Copy the result or export it as a TXT file.

4. Example

5. Things to keep in mind

• Random generation does not guarantee uniqueness: large batches can collide, so run Remove Duplicates before distributing codes;
• A shorter character set and a shorter length mean fewer combinations, so never use very short codes for important scenarios;
• Generation runs entirely in your browser, with no network transfer and nothing uploaded;
• Very large batches can slow the browser slightly, so generate in batches.

6. FAQ