Random String Generator

Random String Generator produces strings of whatever length and alphabet you need, using your browser's cryptographic random number generator rather than Math.random.

That distinction matters more than it sounds. Math.random is a predictable pseudo-random generator: given enough output an attacker can work out its internal state and predict everything it will produce next. For a shuffled list that is harmless; for an API key, a password reset token or a session identifier it is a vulnerability. This page uses crypto.getRandomValues, which is seeded by the operating system and designed for exactly this job.

Selection from the alphabet uses rejection sampling rather than a modulo. A naive modulo makes the first few characters of the alphabet very slightly more likely than the rest, and that bias is measurable and avoidable, so it is avoided.

Character sets are configurable because requirements differ. Hexadecimal for tokens that go in URLs, alphanumeric for things people may have to read aloud, the full printable set for maximum entropy per character, or an unambiguous set with no confusable characters for codes that get typed by hand.

Everything runs inside your browser. Nothing you paste is uploaded, logged or stored, which matters when the input is a client list, an internal URL map or anything else you would not post publicly.

• Uses crypto.getRandomValues, not Math.random
• Rejection sampling, so no character is more likely than another
• Hex, alphanumeric, letters, symbols or unambiguous character sets
• Custom alphabets, including excluding specific characters
• Generate a batch and copy or download it
• Entropy in bits shown for the settings you chose
• Nothing is generated on, or sent to, a server

The random string generator is used by writers, developers, students, marketers and anyone else who needs the job done once without installing software. Common cases include:

• Creating an API key or access token
• Generating test data with unique identifiers
• Producing a one-off invite or coupon code
• Making a random filename or temporary directory name
• Seeding a database with distinct values