What's Base64 used for?

Encoding binary data as plain ASCII text so it can travel through text-only channels: email MIME, JSON, URLs, XML. Common in `data:image/...` URIs for embedding images in HTML/CSS, in Basic HTTP authentication, in JWT tokens (header and payload parts), in API payloads.

Does this handle Cyrillic or emoji?

Yes. The tool encodes and decodes UTF-8 via the browser's TextEncoder / TextDecoder, so any Unicode character (Cyrillic, emoji, CJK) round-trips correctly. Plain `btoa` on its own throws on multi-byte characters, the tool converts to UTF-8 bytes first to avoid that.

Why does the encoded version look ~33% longer?

Base64 uses a 4-character alphabet per 3 bytes of input, so encoded output is always around 33% larger than the original. Worth knowing: do not Base64-encode large files into URLs or JSON if bandwidth matters, keep them binary in dedicated uploads.

What about `==` at the end?

That is padding. Base64 encodes in 3-byte chunks → 4 output characters. If your input length is not a multiple of 3, the last group is padded with `=` to keep the 4-character shape. One leftover byte → `==`, two leftover bytes → `=`. Some pipelines strip the padding (URL-safe Base64). This tool always emits standard Base64 with padding.

Where is the encoding done?

Entirely in your browser via the built-in `btoa` / `atob` plus TextEncoder. Nothing leaves your device. For URL percent-encoding (a different scheme) use URL Encoder.

Free, no signup, no rate limit (everything runs client-side).

Utility

Base64 Encode/Decode

Encode and decode Base64

Input

Mode

Text to Encode

Convert binary data or text to Base64 format and back. Essential for data transport in email (MIME) and JSON.

Terminal

Console ready. Execute a command to see output...

About Base64 Encode/Decode

Binary to Text

Base64 schemes represent binary data in an ASCII string format. It is commonly used to embed images in HTML (data:image/...) or send complex data via simple text protocols.

How it increases size

Base64 encoding increases the size of the data by approximately 33%. It takes 3 bytes of input and outputs 4 characters. This is why you shouldn't Base64 encode very large files if bandwidth is a concern.

How to use Base64 Encode/Decode

Pick Encode or Decode
Toggle the mode button at the top.
Paste the input
Either plain text (for Encode) or a Base64 string (for Decode) into the textarea.
Hit the button
The result is printed into the terminal panel.

Frequently Asked Questions

: Encoding binary data as plain ASCII text so it can travel through text-only channels: email MIME, JSON, URLs, XML. Common in data:image/... URIs for embedding images in HTML/CSS, in Basic HTTP authentication, in JWT tokens (header and payload parts), in API payloads.