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Random String Generator

Generate random strings for IDs, keys, tokens, and test data, with control over length, character sets, and how many you make at once.

Random string

Generating a random string.

Entropy per string~95 bits

Generated on your device. Nothing is sent or stored.

Characters

Each character is drawn uniformly from the sets you enable. Look-alikes are 0, O, 1, l, I and the vertical bar.

Amount

How to generate a random string online

  1. Get a string instantly

    A random string of uppercase, lowercase, and digits appears as soon as the page loads.

  2. Set length and character sets

    Drag the length slider and toggle uppercase, lowercase, digits, and symbols, with an option to exclude look-alike characters; the string rerolls with every change.

  3. Generate a batch

    Switch the amount to 5, 20, or 50 to make a list of random strings at once, each one drawn independently.

  4. Copy the result

    Copy a single string with one click, or copy the whole batch as a newline separated list.

Why use this tool

Full character-set control

Toggle uppercase, lowercase, digits, and symbols in any combination to match the format a field or key requires.

Length and batch size

Set any length up to 128 characters and generate 1, 5, 20, or 50 strings at once for seeding test data or issuing tokens.

Entropy estimate in bits

A live readout shows the entropy of each string for the current settings, so you can see how hard it would be to guess.

Look-alike exclusion

One toggle removes 0, O, 1, l, I and the vertical bar for strings that have to be read aloud or typed by hand.

Generated on your device

Every string is created locally from a cryptographically secure random source and is never sent, stored, or logged anywhere.

About this tool

This random string generator produces random strings on your device for the many jobs that need one: an API key, a test password, a database record ID, a nonce, a cache-busting suffix, or filler data for a form. Choose which characters to draw from, uppercase, lowercase, digits, and symbols, set the length, and a fresh string appears immediately. Nothing follows a predictable pattern; every character comes from a cryptographically secure random source, the same quality of randomness browsers use for encryption.

Each character is picked uniformly at random from the pool you enable, so a string with more character types and more length is harder to guess. The readout under the result shows that difficulty as entropy in bits, roughly the base-two logarithm of the pool size multiplied by the length. A 16 character string over the full 88 character set carries about 103 bits, while a shorter digits-only string carries far less. When a string has to be read over the phone or copied from paper, the look-alike option drops 0, O, 1, l, I and the vertical bar so it cannot be misread.

Because everything happens in your browser, no server ever sees the values, which matters when the string is a secret. Generate 1, 5, 20, or 50 at a time and copy them as a newline separated list for seeding fixtures or issuing batch credentials. For account passwords with a strength meter use the password generator, for unique identifiers reach for the UUID generator, and for whole-number draws see the random number generator.

Frequently asked questions

How are the random strings generated?
Each character is drawn from your browser's cryptographically secure random source, the same quality of randomness used for encryption keys, and picked uniformly so no character is more likely than another. Selection uses rejection sampling, which means there is no bias toward any part of the character set.
What does the entropy estimate mean?
Entropy, measured in bits, estimates how hard a string is to guess. It is the base-two logarithm of the number of possible characters multiplied by the length. Every extra bit doubles the number of guesses required, so adding length or another character set raises it quickly.
Which characters can I include?
You can turn uppercase letters, lowercase letters, digits, and symbols on or off in any combination, and at least one set always stays on. The exclude look-alikes option removes 0, O, 1, l, I and the vertical bar so the string is easy to read and type.
Are the strings sent or stored anywhere?
No. Every string is generated entirely on your device and never leaves your browser. Nothing is uploaded, logged, or saved; once you leave the page the values are gone unless you copied them.
What are the limits?
Strings can be up to 128 characters long across four character sets, and you can generate 1, 5, 20, or 50 at once. Because everything runs locally there are no rate limits, and you can regenerate as often as you like.

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