Tool Fu
$ toolfu run base64-encoder

Base64 Encoder & Decoder — Online Free

Free online Base64 encoder and decoder. Encode text to Base64 or decode Base64 strings instantly. Base64 converter with Unicode support — runs entirely in your browser.

all processing runs in your browser
base64-encoder
input > plain text
output > base64 encoded
encoded output will appear here

Base64 Encode and Decode Online — Free Base64 Converter

Base64 encoding is one of the most common operations in web development. Whether you're embedding images in CSS, transmitting binary data in JSON APIs, encoding email attachments, or working with data URIs, you need a quick way to encode and decode Base64 strings.

This tool converts between plain text and Base64 in real time as you type. It properly handles Unicode by encoding text as UTF-8 before Base64 conversion, so emoji, accented characters, and CJK text all work correctly. Everything runs in your browser — your data never leaves your device.

When to use Base64

  • Embedding images as data URIs in HTML or CSS
  • Transmitting binary data through text-based APIs
  • Encoding file contents for JSON payloads
  • Basic HTTP authentication headers
  • Encoding email attachments (MIME)

How Base64 works

Base64 takes every 3 bytes of input and maps them to 4 printable ASCII characters from an alphabet of 64 characters (A-Z, a-z, 0-9, +, /). If the input length is not a multiple of 3, the output is padded with = characters. This makes Base64 output about 33% larger than the input, but guarantees it is safe for text-based transport.

$ cat FAQ.md
What is Base64 encoding?▶
Base64 is a binary-to-text encoding scheme that converts binary data into a string of ASCII characters. It uses 64 characters (A-Z, a-z, 0-9, +, /) plus = for padding. It's commonly used to embed binary data in text-based formats like JSON, HTML, or email.
Why is Base64-encoded data larger than the original?▶
Base64 encoding increases data size by approximately 33%. This is because every 3 bytes of input are encoded as 4 ASCII characters. The tradeoff is that the encoded data is safe to transmit through text-based protocols that might otherwise corrupt binary data.
Is Base64 encryption?▶
No. Base64 is an encoding scheme, not encryption. Anyone can decode a Base64 string — there is no key or secret involved. Never use Base64 to protect sensitive data. It is designed for safe data transport, not security.
Does this tool handle Unicode text?▶
Yes. This tool properly handles Unicode characters by encoding the text as UTF-8 before applying Base64 encoding. This means you can safely encode emoji, accented characters, CJK characters, and other non-ASCII text.