Why Never Use Base64 for Passwords

When building applications, handling user passwords securely is one of the most critical responsibilities. A common beginner mistake is confusing encoding (like Base64 or URL encoding) with encryption or hashing.

The Misconception

Some developers might think, “If I turn the password into a random-looking string of characters, it’s safe, right?”

// DON'T DO THIS
const password = "mysecretpassword";
const encoded = btoa(password); 
console.log(encoded); // "bXlzZWNyZXRwYXNzd29yZA=="

This looks unreadable to a human, but it is not secure.

Encoding vs. Hashing

Base64 Encoding

Base64 is a binary-to-text encoding scheme. It is designed to transport data, not protect it. It is a two-way process. You can see this in action using our Base64 Encoder tool to instantly encode and decode any text.

• Public Algorithm: Everyone knows how Base64 works.
• Reversible: Anyone can decode it instantly without a key.

// Decoding is trivial
const decoded = atob("bXlzZWNyZXRwYXNzd29yZA==");
console.log(decoded); // "mysecretpassword"

If you store passwords as Base64 in your database, and your database leaks, every single user account is immediately compromised.

Hashing

Hashing is a one-way process. You transform the data into a fixed-size string of characters, which cannot be reversed to get the original data.

• One-way: You can’t turn the hash back into the password.
• Verification: To check a password, you hash the user’s input and see if it matches the stored hash.

Property	Base64 (Encoding)	Bcrypt / Argon2 (Hashing)
Reversible?	Yes, instantly	No
Needs a key?	No	No
Safe to store passwords?	Never	Yes
Designed to be slow?	No	Yes (on purpose)
Protects against leaks?	No	Yes

What to use instead?

Use industry-standard hashing algorithms designed for passwords, such as:

1. Argon2 (Recommended)
2. Bcrypt
3. Scrypt

These algorithms are “slow” by design, making it computationally expensive for attackers to guess passwords using brute-force attacks.

Why “Slow” Hashing Is a Feature, Not a Bug

General-purpose hashes like MD5 or SHA-256 were built to be fast — billions of operations per second on modern hardware. That speed is great for checksums, but disastrous for passwords: an attacker with a leaked database can try billions of guesses per second too.

Password hashing functions like Bcrypt and Argon2 deliberately add a tunable work factor (cost). You can dial the cost up over the years as hardware gets faster, so a 2026 hash stays expensive to crack in 2030.

Always Add a Salt (and Bcrypt/Argon2 Do This for You)

A salt is a unique random value added to each password before hashing. Salts ensure that two users with the same password get completely different hashes, and they defeat rainbow tables (precomputed lookup tables of common password hashes).

The good news: Bcrypt and Argon2 generate and embed a unique salt automatically, so you don’t have to manage it yourself. This is another reason to use a purpose-built library instead of rolling your own with btoa() or a bare SHA.

A Quick Real-World Example

// ❌ Insecure: encoding only
const stored = btoa("hunter2"); // "aHVudGVyMg==" — trivially decoded

// ✅ Secure: hashing with a per-user salt (bcryptjs)
import bcrypt from "bcryptjs";
const hash = await bcrypt.hash("hunter2", 12); // cost factor 12
const ok = await bcrypt.compare("hunter2", hash); // true

If your database leaks the btoa version, every password is exposed in seconds. If it leaks the bcrypt version, an attacker faces years of brute-forcing per account.

Frequently Asked Questions

Q: Is Base64 encryption? A: No. Encryption requires a secret key and is reversible only with that key. Base64 needs no key and anyone can decode it. Try our Base64 Encoder tool and decode the output yourself to see how trivial it is.

Q: Is it safe to store passwords as SHA-256? A: No. SHA-256 is a fast, general-purpose hash with no salt and no work factor, which makes it vulnerable to brute-force and rainbow-table attacks. Use Bcrypt, Argon2, or Scrypt instead.

Q: Should I ever use Base64 at all? A: Yes — for its intended purpose: safely transporting binary data (images, tokens, attachments) as text. Just never treat it as a security measure.

Summary

• Base64: Just a different representation of data. Zero security.
• Hashing: A mathematically irreversible, salted, deliberately slow transformation. Secure.

Never use Base64, raw MD5, or plain SHA hashes for password storage. Use a battle-tested library that implements Argon2 or Bcrypt — and if you need to understand the difference between encoding and encryption first, start with our Base64 Encoder tool and our guide on URL encoding.