What is a password salt?

A salt is a random string appended or prepended to a password before it is hashed. Because each user has a unique salt, two users with the same password will have different hashes. This defeats precomputed rainbow table attacks and forces an attacker to brute-force each account independently.

How long should a salt be?

NIST SP 800-132 recommends at least 128 bits (16 bytes). Most modern libraries (bcrypt, Argon2) generate a 128-bit or 256-bit salt automatically. For custom implementations, 16–32 bytes is the practical standard.

Which format should I use?

Hex is the most portable and human-readable. Base64 is 33% shorter than hex and common in many frameworks. Base64url is preferred when the salt is embedded in a URL or JWT. The decimal array is useful when you need raw bytes as a JSON value.

Should I generate my own salts, or let the library do it?

If you use bcrypt, Argon2id, or scrypt through a well-maintained library, the library handles salt generation for you — you should not pass a custom salt. Use this tool for learning, custom implementations, nonce generation, or migration scripts.

Is this tool safe to use?

Yes. All generation happens in your browser. No data is sent to any server. The entropy source is window.crypto.getRandomValues, the same API used by TLS libraries.

Password Salt Generator

Name: Password Salt Generator
Availability: InStock
Author: Nham Vu

Generate cryptographically secure random salts for password hashing. Choose length, output format, and quantity — pure client-side using window.crypto.getRandomValues.

Salt Options

Salt Length

Entropy: 256 bits

Output Format

Quantity: 1

Generated Salts

Click "Generate New Salt" to start

How to use this salt

Copy the hex value and pass it to your hashing function. Example with bcrypt (Node.js):

const salt = await bcrypt.genSalt(12);
// Or with a manual salt prefix (legacy):
const hash = await bcrypt.hash(password, salt);

Note: bcrypt generates its own salt internally. Use these salts for PBKDF2, Argon2, or custom HMAC constructions.

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Summary

Generate cryptographically secure random salts for password hashing. Choose length, output format, and quantity — pure client-side using window.crypto.getRandomValues.

How it works

window.crypto.getRandomValues fills a Uint8Array with cryptographically random bytes from the operating system's entropy pool. The bytes are then encoded into your chosen format: hex (two lowercase hex digits per byte), base64 (standard RFC 4648 encoding), base64url (URL-safe variant replacing + with - and / with _), or a decimal byte array (JSON array of integers 0–255). Entropy is calculated as bytes × 8 bits.

Use cases

Generating salts for bcrypt, Argon2, or PBKDF2 before storing a new user password.
Creating unique per-row salts for a legacy MD5/SHA-1 password column migration.
Producing random nonce values for HMAC-based token generation.
Supplying test vectors of known entropy for security unit tests.
Teaching developers why salts prevent rainbow table attacks.

Frequently Asked Questions

Last updated: 2026-06-09 · Reviewed by Nham Vu