Base64 Encoder & Decoder

What is Base64?

Base64 is a binary-to-text encoding scheme that represents raw bytes using 64 printable ASCII characters (A–Z, a–z, 0–9, +, /). It's the standard way to embed binary data — images, keys, certificates, payloads — inside text-only contexts like JSON, XML, HTTP headers, and email (MIME).

How to Base64 encode or decode

1. 1Choose Encode or Decode at the top of the tool.
2. 2Paste your text (for encode) or Base64 string (for decode) into the input area.
3. 3The result appears instantly on the right — no button click required.
4. 4Toggle URL-safe mode if the output will be placed in a URL or filename (replaces +/ with -_).
5. 5Click Copy to grab the result.

Use Cases

Code Examples

// Encode
const encoded = btoa("hello");
// Decode
const decoded = atob(encoded);

// btoa/atob only handle Latin1. For UTF-8:
const encoded = btoa(unescape(encodeURIComponent("你好")));
const decoded = decodeURIComponent(escape(atob(encoded)));

import base64
b = base64.b64encode(b"hello").decode()
plain = base64.b64decode(b).decode()

import "encoding/base64"

encoded := base64.StdEncoding.EncodeToString([]byte("hello"))
decoded, _ := base64.StdEncoding.DecodeString(encoded)

# macOS/Linux
echo -n "hello" | base64        # encode
echo "aGVsbG8=" | base64 -d       # decode

Key Concepts

URL-safe Base64

A variant that replaces `+` with `-` and `/` with `_` so the result is safe in URLs, file names, and JWT tokens without further percent-encoding.

Base64URL

Same as URL-safe Base64, additionally omitting the `=` padding. Used inside JWTs (header, payload, and signature).

MIME Base64

The email variant: same alphabet as standard Base64, but wraps output at 76 characters per line.

Padding (=)

Base64 output length must be a multiple of 4. Missing bytes at the end are padded with `=`. Some parsers accept unpadded input — some don't.

Tips & Best Practices

• ▸Base64 encoding grows the payload by ~33%. For images larger than ~10 KB, HTTP-link them instead of inlining.
• ▸Base64 is encoding, not encryption. Anything you Base64 can be trivially decoded — never use it to 'hide' secrets.
• ▸When decoding fails, check for line breaks (`\n`) or spaces in the input — some parsers reject them, some accept them.
• ▸For URL-safe or JWT contexts, remember to also strip `=` padding — Base64URL is not the same as standard Base64.