Base64 Encoder & Decoder

Encode text to Base64 or decode Base64 strings instantly. All processing happens in your browser - no data is sent to any server.

Text to Encode

URL-safe encoding (replace +/ with -_)

Remove padding (=)

Base64 Output

Base64 to Decode

URL-safe input (convert -_ to +/)

Decoded Output

Base64 Reference

What is Base64?

Base64 is a binary-to-text encoding scheme that represents binary data using 64 printable ASCII characters. It's commonly used for:

Encoding binary data in emails (MIME)
Embedding images in HTML/CSS (data URIs)
Encoding credentials in HTTP Basic Authentication
Storing binary data in JSON/XML
JWT (JSON Web Tokens) encoding

Base64 Alphabet

Standard Base64:
A-Z (0-25), a-z (26-51), 0-9 (52-61), + (62), / (63)
Padding character: =

URL-Safe Base64:
A-Z (0-25), a-z (26-51), 0-9 (52-61), - (62), _ (63)
(Replaces + with - and / with _)

Size Overhead

Base64 encoding increases data size by approximately 33% (4 output characters for every 3 input bytes).

Original:  3 bytes  = 24 bits
Encoded:   4 chars  = 24 bits (6 bits per character)

Formula: encoded_size = ceil(original_size / 3) * 4

Common Base64 Examples

Original	Base64 Encoded
Hello	SGVsbG8=
Hello World	SGVsbG8gV29ybGQ=
admin:password	YWRtaW46cGFzc3dvcmQ=
{"user":"test"}	eyJ1c2VyIjoidGVzdCJ9

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Related Resources

🔐 Encryption Cheat Sheet Encryption algorithms guide 🎟️ JWT Decoder Decode JSON Web Tokens

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