Generate Secure Random Bytes for Keys and Salts

To generate secure random bytes online, open the ByteTools Random Buffer Generator, enter the size you need, pick hex, Base64 or a binary file, and click Generate — the bytes come from crypto.getRandomValues, the same operating-system CSPRNG real cryptography relies on, and never leave your browser. No server, no logging, no network round trip.

Random bytes are the raw material behind almost every security primitive: signing keys, encryption keys, salts, initialization vectors, nonces and tokens all start life as a buffer of unpredictable bytes. Getting that buffer right — the correct size, the correct encoding, and a genuinely secure source — is what this tool makes trivial.

Why the source of randomness matters

Not all randomness is equal. A general-purpose PRNG like Math.random() is designed to be fast and statistically even, not unpredictable — an attacker who sees a few outputs can often reconstruct the internal state and predict the rest. For anything an adversary could benefit from guessing, you need a cryptographically secure random number generator. This tool draws every byte from crypto.getRandomValues, which is backed by the OS entropy pool, so the output is suitable for real keys and secrets rather than just test noise.

How to generate a random buffer in your browser

1. Enter the size and choose the unit — bytes for precise key sizes, or KB when you need a larger blob.
2. Pick an output format: hex for readability, Base64 for compact config values, or a downloadable binary file.
3. Click Generate to fill the buffer with secure random bytes.
4. Copy the encoded string with one click, or download the raw bytes as a .bin file for test uploads.

How many bytes do you actually need?

Oversizing wastes nothing, but undersizing weakens security. Here are the sizes that map to common real-world uses so you can pick with confidence.

Use case	Recommended size	Notes
Symmetric / HMAC key	32 bytes (256-bit)	Standard for AES-256 and JWT HS256 signing
AES IV / nonce	16 bytes	12 bytes for AES-GCM specifically
Password salt	16 bytes	Unique per user, stored alongside the hash
Session / cookie secret	32–64 bytes	Longer is fine for long-lived secrets

As a rule, 32 bytes is already far beyond guessable, so when in doubt reach for a 256-bit buffer.

Hex or Base64 output?

Both encode the exact same bytes, just differently. Hex uses two characters per byte, so a 32-byte key becomes 64 characters — easy to read, compare and paste into most tools. Base64 packs about 1.33 characters per byte, so the same key is only 44 characters, which is handier for environment variables, headers and JSON config. Choose whichever your target system expects.

Key features and benefits

• Cryptographically secure bytes via crypto.getRandomValues.
• Size in bytes or KB, scaling up to multi-megabyte buffers.
• Hex, Base64 or raw binary file output.
• One-click copy and .bin download.
• Chunked generation handles large buffers without errors.
• 100% client-side and offline-capable.

Try the Random Buffer Generator now — it's free and runs entirely in your browser.

Frequently asked questions

Are these bytes safe to use as real encryption keys?

Yes. They come from crypto.getRandomValues, which is backed by your operating system's cryptographically secure generator — the same source used by production crypto libraries. A 32-byte buffer gives you a standard 256-bit key.

Why does the tool generate in chunks?

Browsers cap a single crypto.getRandomValues call at 65,536 bytes. For anything larger, the tool simply calls it repeatedly and stitches the pieces together, so you can create megabytes of randomness without hitting that limit.

Can I use Math.random() instead for convenience?

Not for anything security-sensitive. Math.random() is a predictable, non-cryptographic PRNG whose sequence can be reconstructed from a handful of samples. Always use CSPRNG output for keys, tokens, salts and nonces.

What's a good use for the binary file download?

The .bin download gives you a file of pure random data at an exact size, which is perfect for testing upload limits, streaming code, or storage systems — without shipping any real or sensitive content.

Is a bigger buffer always more secure?

More bytes never reduce security, but there is a point of diminishing returns. Beyond 32 bytes the key is already computationally impossible to brute-force, so extra length is mostly relevant for specific protocol requirements rather than added safety.

Related free tools

• UUID Generator — secure v4 identifiers in bulk.
• Password Generator — strong human-usable passwords.
• Random Number Generator — secure numbers in any range.
• Base64 Encoder — encode and decode Base64 strings.

Built by ByteVancer

ByteTools is a free product of ByteVancer, a software and web development studio that builds web apps, SaaS platforms and custom software for businesses. Need a secure system built properly from the ground up? Explore ByteVancer's services and start a conversation about your project.