How much entropy do I have?

Roughly length multiplied by log2 of the alphabet size. Twenty characters from a 62-character alphabet is about 119 bits — far beyond guessable.

Random String Generator

Build random strings from a character set you control.

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About this tool

Generates random strings from a character set you choose, drawn from the platform CSPRNG. Useful for fixtures, test data and one-off tokens.

Limitations

Randomness comes from the Web Crypto API. Math.random() is never used here.

Questions

How much entropy do I have?: Roughly length multiplied by log2 of the alphabet size. Twenty characters from a 62-character alphabet is about 119 bits — far beyond guessable.

Privacy

This page does its work in your browser. What you paste is processed by JavaScript running on your own device and is never sent to a DevToolery server — there is no server that could receive it. The page itself is a static file delivered by a CDN. See exactly what is stored.