Encoding utility

Base64 Encoder & Decoder

A fast, private Base64 encoder and decoder for UTF-8 text, Unicode, emoji, and URL-safe Base64 values.

Text utility

Converter workspace

Choose a direction, add your value, and convert it instantly.

Runs locally in your browser

0 characters

Unicode characters and emoji are supported.

0 result characters
Base64 field guide

What is Base64, and when should you use it?

Base64 turns bytes into a predictable set of printable characters so binary or Unicode data can travel through text-oriented systems. It is a transport encoding—not compression, encryption, or a way to protect data.

What is Base64?

Base64 is a binary-to-text encoding defined by RFC 4648. It maps each 6-bit value to one of 64 ASCII characters: uppercase letters, lowercase letters, digits, and two symbols. An optional = character completes the final four-character group when the input byte count is not divisible by three.

Text must become bytes before it can be encoded. This tool uses UTF-8, so Unicode text and emoji are first represented as UTF-8 bytes and then converted to Base64. Decoding reverses those steps.

How Base64 encoding works

Three 8-bit bytes become four 6-bit alphabet indexes.

UTF-8 input
Man
Three bytes
4D 61 6E
Four characters
TWFu

RFC 4648 groups 24 input bits—three bytes—and divides them into four 6-bit values. Because every three input bytes normally produce four text characters, Base64 output is roughly one-third larger than the original data before line wrapping or surrounding format overhead.

Base64 vs base64url

The bit conversion is the same; two alphabet characters differ.

Variant Values 62 and 63 Padding Choose it for
Base64 + and / = completes the final group unless another specification says otherwise General text protocols and formats that explicitly expect standard Base64
base64url - and _ May omit = when the data length is known implicitly URLs, filenames, and formats that explicitly require the URL-safe alphabet

Practical rules for choosing and decoding

Match the format

Use the required alphabet

Do not swap Base64 and base64url by assumption. The surrounding API, file format, or protocol should name the expected variant.

Text first

Agree on UTF-8

Base64 preserves bytes, not character meaning. Both sides must use the same character encoding when those bytes represent text.

Validate input

Reject malformed data

Unexpected characters or impossible padding can signal corruption. Decode according to the rules of the format that carries the value.