Random Bytes Generator

The number of random bytes sets how hard a value is to guess: each byte adds 8 bits of entropy. These sizes cover most uses.

Hex uses two characters per byte and is the most common way to write keys in configuration files and documentation. Base64 is about a third shorter and is used in JSON, HTTP headers and many APIs. Base64url replaces + and / with - and _ and drops padding, so values can be used safely in URLs, file names and JSON Web Tokens. The byte array format writes values like 0x1f, ready to paste into C, Rust, Go or JavaScript source code. Binary shows each byte as eight 0s and 1s, which is mostly useful for teaching.

crypto.getRandomValues is defined by the Web Cryptography standard to return cryptographically strong values. Browsers fill it from the operating system's generator — the same source used for TLS keys — which is seeded from hardware events and, on modern processors, dedicated hardware random number instructions. Values are generated locally, never fetched from a server, so nobody else ever sees them, and they are not kept after you close the page.

Generate a new value for each purpose rather than reusing one key everywhere. Store secrets in a password manager or a secrets vault, not in source code or chat messages. A nonce for AES-GCM must never be reused with the same key — generate a fresh one for every message. Remember that hex and Base64 are just ways of writing the same bytes: a 32-byte key is 64 hex characters or 44 Base64 characters, but it is still 256 bits of randomness.

For passwords people type, use the Password Generator; for short numeric codes, the PIN Generator; for API keys with prefixes, the API Key Generator; and for unique identifiers, the UUID Generator. To turn a password into a key, use the PBKDF2 Generator, and to encrypt text or files with a password, use AES Encryption.