Why this pattern string generator?
- Create business-style IDs from dates, sequences, and random tokens.
- Preview first 20 lines and export in multiple formats.
- Share settings safely—output never appears in URLs.
- Seeded mode enables reproducible test data.
Quick presets
Pick a preset to fill the pattern box, then tweak tokens as needed.
Generate
Pattern string generator
Enter a pattern, choose output settings, then generate lines, CSV, or JSON array.
Token reference
| Token | Example | Description |
|---|---|---|
{A:n} |
{A:3} |
Uppercase letters (A-Z). |
{a:n} |
{a:4} |
Lowercase letters (a-z). |
{9:n} |
{9:6} |
Digits (0-9). |
{alnum:n} |
{alnum:8} |
Alphanumeric (A-Z, a-z, 0-9). |
{hex:n} |
{hex:8,upper=true} |
Hex characters, optional uppercase. |
{chars:n,SET} |
{chars:10,ABCDEFGHJKLMNPQRSTUVWXYZ23456789} |
Random characters from a custom set. |
{uuid} |
{uuid} |
UUID v4 string. |
{date:FORMAT} |
{date:YYYYMMDD} |
Generation time formatted as YYYY MM DD HH mm ss. |
{randdate:start,end} |
{randdate:2025-01-01,2025-12-31,format=YYYY-MM-DD} |
Random date/time between start and end (local time). |
{randint:min,max} |
{randint:0,999999,pad=6} |
Random integer in range, optional zero padding. |
{choice:v1|v2} |
{choice:BUG|REQ|SUP} |
Pick one of the listed values. |
{seq} |
{seq:pad=6,start=1} |
Sequential numbers (start/step/pad). |
Examples
- INV-{date:YYYYMM}-{seq:pad=6,start=1} → INV-202601-000001
- ORD-{date:YYYYMMDD}-{hex:8} → ORD-20260119-3f8a9c1d
- DLV-{randdate:2025-01-01,2025-12-31,format=YYYYMMDD}-{chars:6,ABCDEFGHJKLMNPQRSTUVWXYZ23456789} → DLV-20250714-K8Q2ZP
- USR-{A:3}{9:6} → USR-ABC123456
- X\{Y\}-{A:2} → X{Y}-QZ
How to use this tool effectively
Start with a short pattern and a small count, then add one token or rule at a time. This lets you verify date formatting, sequence width, random token length, and whether the pattern is safe to share before you generate a larger batch.
Build the pattern step by step
Choose the closest preset first, then adjust prefixes, date blocks, sequence padding, and random tokens one change at a time. Generate a few lines after each edit so you can spot broken separators or unexpected token output quickly.
Use seeded mode only for repeatability
Use seeded mode when you need teammates to recreate the same sample IDs later. Leave secure mode on when you want less predictable examples and do not need exact replay.
Check unique mode before large runs
Unique generation can fail when the value space is too small for your requested count. Test a short run first if your pattern has a short sequence, a narrow random range, or a small choice list.
Decide what to include in the share URL
- Share URLs never include generated output.
- Turn off include pattern when the pattern contains internal prefixes, customer codes, or other identifiers you should not expose.
- Include the seed only when collaborators need the same deterministic sample.
See also
FAQ
Is my data uploaded?
No. Everything runs locally in your browser.
Can I share generated IDs with a URL?
Share URLs include settings only. Use copy/download to share output.
Is seeded mode secure?
No. Seeded mode is for reproducibility only.
Can I exclude the pattern from share URLs?
Yes. Turn off include pattern and share settings without exposing the pattern.
When should I use seeded mode or exclude the pattern from the URL?
Use seeded mode when you need repeatable test IDs. Exclude the pattern from the URL when it contains internal prefixes, customer codes, or other identifiers that should not be shared.