Random String Generator
Random strings from character-set groups or a token pattern — bulk count, exclude ambiguous, grouping separators, seeded reproducibility, entropy readout, and export as lines / JSON / CSV.
What this tool does
It builds random strings to a length and character set you choose, or to a token pattern, and can generate many at once. It shows how much entropy each string carries.
Character groups vs a pattern
In group mode you tick the sets to draw from — uppercase,
lowercase, digits, symbols, or presets like hex, base58 and
base64url — plus any custom characters. In pattern mode you write a
template where U is an uppercase letter, l
lowercase, L any letter, d a digit,
x a hex digit, s a symbol, *
any of the above, and anything in { } is literal.
Quality controls
Exclude ambiguous characters (0 O o 1 l I), exclude
your own list, require at least one character from every selected
group, and forbid a character repeating immediately.
Secure vs reproducible
By default every character comes from crypto.getRandomValues,
the browser's cryptographic generator. Set a seed and it switches to a
deterministic generator so the same seed and settings always produce
the same strings — useful for fixtures, not for anything that must
stay secret.
Privacy
Generation is entirely local. Nothing is transmitted.