Base64 Encode Online

What Is Base64 Encoding?

Base64 is a binary-to-text encoding scheme that represents binary data using a set of 64 printable ASCII characters. It was designed to safely transport binary data through systems that only handle text — such as email (MIME), HTTP headers, and XML. The name "Base64" comes from the 64 characters used in the encoding alphabet.

The encoding works by taking three bytes of input (24 bits) and splitting them into four 6-bit groups. Each 6-bit value maps to one character in the Base64 alphabet. If the input length is not a multiple of three, padding characters (=) are appended to reach a multiple of four output characters. The result is a string that is approximately 33% larger than the original data but safe to transmit as plain text.

Why Use This Tool?

This encoder handles Unicode text correctly, supports both standard and URL-safe variants, and encodes entirely in your browser — your data never leaves your machine.

How to Use This Base64 Encoder Online

No account, no install, no upload — paste text and the encoded output appears instantly.

1. 1
   Paste or Type Your Text

   Click the input field and paste any text — plain strings, JSON payloads, API keys, email addresses, or any UTF-8 content. Encoding updates live as you type.
2. 2
   Choose Your Variant

   Select Standard (RFC 4648) for MIME, HTTP Basic Auth, and general use. Select URL-safe for JWT tokens, query string parameters, filenames, and any context where + or / would break URL parsing.
3. 3
   Copy the Output

   Click Copy to send the Base64 string to your clipboard in one click. The output is ready to paste directly into your code, config file, or API request.
4. 4
   Use in Your Application

   Paste the encoded string wherever needed — Authorization headers, data URIs, JSON fields, environment variables, or Kubernetes secrets. For URL-safe output, padding is already stripped.

The Base64 Alphabet

Base64 uses 64 characters: uppercase A–Z (values 0–25), lowercase a–z (26–51), digits 0–9 (52–61), and two special characters for values 62 and 63. The standard RFC 4648 variant uses + and /; the URL-safe variant replaces them with - and _ to avoid conflicts in URLs and filenames.

Standard vs URL-safe Base64

The standard Base64 alphabet uses + and / which are special characters in URLs and file paths. The URL-safe variant replaces these with - and _ and typically omits padding = characters. Use URL-safe encoding for JWT tokens, data in query strings, filenames, and any context where + or / would be misinterpreted.

Common Use Cases

When NOT to Use Base64

Base64 is a transport encoding, not a security mechanism. These are the most common misuses that cause real problems in production:

Code Examples

How to Base64-encode a string in popular languages and environments:

// Standard Base64
const encoded = btoa(unescape(encodeURIComponent(text)))

// URL-safe Base64 (no padding)
const urlSafe = btoa(unescape(encodeURIComponent(text)))
  .replace(/\+/g, '-').replace(/\//g, '_').replace(/=/g, '')

// Standard
const encoded = Buffer.from(text).toString('base64')

// URL-safe
const urlSafe = Buffer.from(text).toString('base64url')

import base64

# Standard
encoded = base64.b64encode(text.encode()).decode()

# URL-safe (no padding)
url_safe = base64.urlsafe_b64encode(text.encode()).decode().rstrip('=')

# Standard
echo -n "Hello, World!" | base64

# URL-safe (requires sed)
echo -n "Hello, World!" | base64 | tr '+/' '-_' | tr -d '='

Base64 Encoder Online vs. Other Tools

Several Base64 encoders exist online. The key differentiators for daily developer use are privacy, correctness, and variant support.

Frequently Asked Questions