Random String Generator

Generate secure random strings for API keys, tokens and test data, from preset or custom alphabets.

GeneratorsRuns in your browserFree, no sign-up

Options

Character set

Custom characters

Used only when the set above is "Custom". Duplicates are ignored.

Length

How many

Generated strings

Press Generate to create output.

Ctrl + Enter to run

About the Random String Generator

Generates random strings of a chosen length and character set, from the same cryptographic random source as the password generator. Typical uses are API keys, invite codes, test fixtures and cache-busting suffixes.

Pick the alphabet deliberately. A code a person will read aloud or retype should exclude visually ambiguous characters — 0 and O, 1 and l and I — while a machine-only token benefits from the widest alphabet you can use, because every added character raises the entropy per position.

Frequently asked questions

Why use Crockford Base32?

Because it removes I, L, O and U from the alphabet. Dropping I/L/O eliminates the characters people confuse with 1 and 0 when reading a code aloud or copying it from a screen, and dropping U avoids accidentally spelling offensive words. It is the right choice for anything a human will transcribe: licence keys, recovery codes, short IDs.

How long should an API key be?

At least 128 bits of entropy, which is 22 characters of Base62 or 32 hex characters. The entropy figure shown above the output tells you exactly where you are. Anything under 80 bits should be treated as guessable at scale.

Is a custom alphabet as secure?

The randomness is identical — it always comes from the browser's CSPRNG. But entropy depends on alphabet size, so a 10-character alphabet gives you 3.3 bits per character versus 5.95 for Base62. Duplicates in a custom set are removed so they cannot skew the distribution.

About the Random String Generator

Frequently asked questions

Why use Crockford Base32?

How long should an API key be?

Is a custom alphabet as secure?