Base32 Encoder / Decoder

What Is Base32?

Base32 is a way to represent arbitrary binary data using only 32 printable characters: the uppercase letters A–Z and the digits 2–7.

You're probably more familiar with Base64, which uses 64 characters (A–Z, a–z, 0–9, +, /). So why would you want a smaller alphabet with fewer characters?

Because Base32 makes fewer assumptions about the environment it's used in.

Base64's characters include +, /, and =, which have special meanings in URLs, file systems, and programming languages. You need to use URL-safe variants of Base64 fairly often. Base32's alphabet — only uppercase letters and digits — has no special meaning in virtually any context. It's case-insensitive too, which means JBSWY3DP and jbswy3dp decode to the same thing.

How Base32 Encoding Works

Every Base32 character represents exactly 5 bits of binary data (because 2⁵ = 32). To encode, you:

1. Take the input bytes
2. Convert them to binary
3. Group bits into 5-bit chunks
4. Map each chunk to the corresponding Base32 character

Since bytes are 8 bits, encoding 5 bytes (40 bits) requires exactly 8 Base32 characters (40 ÷ 5 = 8). When the input isn't a multiple of 5 bytes, padding characters (=) are added to reach a multiple of 8 output characters.

Example: Encoding the word Man:

M           a           n
77          97          110        (ASCII decimal)
01001101    01100001    01101110   (binary)

Combined: 010011010110000101101110
Grouped:  01001 10101 10000 10110 1110
As Base32: J     V     Q     W     4
Result: JVQW4 (with padding: JVQW4===)

Base32 vs Base64: When to Choose Which

Choose Base32 when:

• The encoded string will appear in a URL without escaping
• You need case-insensitive comparison
• The string will be typed by hand (fewer confusable characters)
• You're working with TOTP/HOTP secret keys

Choose Base64 when:

• You're embedding in JSON, XML, or HTTP
• File size matters and you want the most compact encoding
• You're transmitting binary data in email (MIME)

The Most Important Use Case: TOTP Secret Keys

If you've ever set up two-factor authentication (2FA) and scanned a QR code, or seen a st...