Base64 Encoder & Decoder

What is Base64 Encoder & Decoder?

A Base64 encoder and decoder that converts in both directions, handles multi-byte UTF-8 characters correctly, and supports the URL-safe variant that swaps + and / for - and _. Encoding and decoding both run in the browser, so your content never leaves the device.

How to use Base64 Encoder & Decoder

1. 1Type or paste plain text or a Base64 string into the left pane.
2. 2Choose the direction — encode or decode — and the result appears as you type.
3. 3Tick the URL-safe option when the output has to go into a URL or a JWT.
4. 4If decoding fails, check whether the string was truncated or is missing its = padding.

How do I do this in code?

Use the tool above for one-off work; for anything you repeat, move it into a script or your project.

// Handle non-ASCII text correctly: convert to UTF-8 bytes first
const encode = (text) =>
  btoa(String.fromCharCode(...new TextEncoder().encode(text)));

const decode = (b64) =>
  new TextDecoder().decode(
    Uint8Array.from(atob(b64), (c) => c.charCodeAt(0)),
  );

Common errors and how to fix them

Frequently asked questions