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 string of uppercase letters and numbers, you've encountered Base32.

TOTP (Time-based One-Time Password) — the standard behind Google Authenticator, Authy, and most 2FA apps — stores shared secrets in Base32 format. When a site gives you a backup code like:

JBSWY3DPEBLW64TMMQ======

...that's a Base32-encoded 20-byte secret key. Your authenticator app decodes it back to bytes, then uses the current time and an HMAC-SHA1 algorithm to generate your 6-digit code.

Our converter lets you:

• Decode these secret keys to see the raw bytes
• Encode test secrets for building your own 2FA implementation
• Verify Base32 strings during debugging

Other Real-World Uses

File integrity checksums in DNS: DNSSEC zone keys and DS records are often Base32-encoded for inclusion in DNS TXT records, since DNS is case-insensitive.

Crockford Base32: A variant developed by Douglas Crockford avoids ambiguous characters like O vs 0 and I vs 1 and L. Used in some ID generation systems for human readability.

Onion addresses: Tor's .onion addresses use Base32 to encode 10 bytes of the host's public key into a 16-character string (3g2upl4pq6kufc4m.onion).

How to Use the Tool

Encode (Text → Base32):

1. Paste or type your plain text in the input box.
2. The tool converts it to bytes using UTF-8, then Base32-encodes it.
3. Copy the result — it's safe to use in URLs, DNS records, or config files.

Decode (Base32 → Text):

1. Paste a Base32 string (letters A-Z and digits 2-7, optional = padding).
2. The tool decodes it and shows the original text or raw bytes.
3. Invalid characters are flagged so you can spot typos quickly.

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