Random String Generator

String length

How many

Alphabet

Advanced options

Prefix

Result

ResultzYZ7PNlSDNfXezuxIX4voer01yXP1dhJ
Entropy, bits191
Alphabet size62

Random identifiers with the entropy stated

Generate random strings of any length from several alphabets, with an entropy estimate and an optional prefix.

Test fixtures, API keys and one-off identifiers all need strings that are unpredictable and the right shape for where they are going.

The entropy figure tells you how much randomness you are actually getting. A 32-character alphanumeric string carries about 190 bits, which is far beyond anything brute force can reach.

What this calculator shows

Random strings at your chosen length and count
Alphabet options including hexadecimal and URL-safe
The entropy in bits, so the strength is explicit

What to keep in mind

Uses the browser's random generator and never sends anything to a server.
For production secrets, generating server-side with a cryptographic source remains the safer practice.

FAQs

How long should an API key be?

Thirty-two characters of alphanumeric is a solid default at roughly 190 bits. Beyond that you are adding length without adding meaningful security.

What does URL-safe mean?

It replaces + and / with - and _, so the string can sit in a URL or filename without needing to be escaped.

Is this safe for production secrets?

The browser's generator is cryptographically sound, but production secrets are better generated server-side, where they never touch a browser at all.

What is entropy in bits?

A measure of how many guesses an attacker needs. Each bit doubles the work, so 128 bits is already beyond reach of any realistic brute-force effort.

Worked example

An API key with a prefix

Input: 32 characters, alphanumeric, prefix sk_live_

Output: A key carrying about 190 bits of entropy

Note: The visible prefix is a convention worth copying — it makes a leaked key instantly identifiable in logs and code.

Useful links

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Random String Generator

Result

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