Serial Number Generator

Features

• Two modes: sequential serial numbers, or random keys from a pattern
• Your own prefix and suffix (the fixed parts of an order number, student ID or batch code)
• Key patterns with `X` (letter or digit), `A` (letter) and `N` (digit) placeholders, mixable freely
• Adjustable start and step, and a negative step numbers backwards
• Zero padding with a configurable width, 4 by default; 0 means none, and negatives are left unpadded so `00-1` never appears
• Key alphabet omits `0 O 1 I L`, and rejection sampling keeps every character equally likely
• Up to 5000 numbers at a time
• Output separated by line breaks, spaces or commas, ready to paste into a sheet, a sentence or a shell
• Every option takes effect immediately
• Runs locally with no requests — the keys you generate never show up in anyone else’s logs

How to use

1. Choose the mode: sequential numbers or random keys
2. Sequential: fill in the prefix, suffix, start value, step and padding width
3. Random keys: write a pattern such as `XXXX-XXXX-XXXX-XXXX`, with a prefix or suffix if you want
4. Set how many you need and the separator
5. Click Copy to take the batch

FAQ

Why is zero padding necessary?

Because of string sorting. A list of `ORD-1`, `ORD-10`, `ORD-2` sorts as `ORD-1`, `ORD-10`, `ORD-2` — number ten before number two, which looks like the data is wrong. Padded to four digits (`ORD-0001` … `ORD-0010`) the string order matches the numeric order, and sorting, comparing and deduplicating all behave. This matters especially for identifiers stored as strings in a database.

Can I use the generated keys as real product licence keys?

You can generate them; validating and issuing them is still your job. This tool only rolls unpredictable strings — it makes no network requests and records nothing, which is exactly what makes it suitable (your keys never land in someone else’s logs). Two things to weigh: the 16-character `XXXX-XXXX-XXXX-XXXX` shape carries roughly 78 bits of entropy, which is plenty, but a pattern with few placeholders is not enough (`NNNN` is only ten thousand possibilities); and a leaked key cannot be revoked, so real issuance should match each key against a server-side allowlist.

Why is there no 0, O, 1, I or L in the keys?

Because people misread them. The life of such a string is to be copied into an email, read out over the phone and typed into a box that refuses a paste — and `0/O` and `1/I/L` get confused at every one of those steps. Dropping those five characters takes the alphabet from 36 to 31, costing about 0.2 bits of entropy per character, and saves a great many support tickets. Short IDs and one-time codes are built on the same reasoning.

Can it generate a serial number with the date in it?

Put the date in the prefix — for instance `2026-0927-` — and let the number increment as usual. The tool deliberately has no `{date}` placeholder, because that would make the output depend on the day it was generated; a generator where the same options always give the same result is far easier to check, and changing the date is a one-line edit to the prefix.

How many can it generate at once?

Five thousand. That limit is deliberate: beyond it the result area and the copied text become unwieldy, and the use cases — a batch of staff numbers, a batch of asset tags — do not reach that size. For more, set the start value to just past the end of the previous batch and click again.