Generate a random string

Generate bounded strings from either a 62-symbol alphanumeric alphabet or explicitly supplied Unicode code points.

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ToolRandom String Generator
Input
Output
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How it works

The built-in alphabet contains uppercase and lowercase Latin letters plus digits. Custom input is deduplicated by Unicode code point, then every requested position uses rejection sampling to index that set; seed text replaces Web Crypto with a deterministic stream.

Formula
default alphabet size = 26 uppercase + 26 lowercase + 10 digits = 62
  • Length and row count are required because fixture schemas impose different bounds.
  • The output ceiling is 256 code points per row and 1,000 rows per request.

Worked example

Five 8-character strings
Input
											Length: 8
Count: 5
Seed: fixture-seed
Output
												CIPI3NcQ
mRibmpcQ
1Tf1moI7
8LTQk8Jx
h3ZwjFLj

When to use this

Property-based tests constrain generated parser inputs, UI prototypes populate sample identifiers, and Unicode fixtures exercise punctuation, emoji, or combining-mark handling.

Edge cases

  • aaab contains two distinct choices, not four weighted positions, because duplicate alphabet code points are removed.
  • 😀 is selected as one code point and never split into invalid UTF-16 surrogate halves.
  • A joined emoji or letter-plus-combining-mark sequence contains multiple code points, so requested length can differ from visible grapheme count.

References