Free Online Base64 Encoder & Decoder

  1. Select encode or decode mode
  2. Enter text or Base64 string
  3. Result displays in real-time, click to copy
  4. For URL usage, enable URL-safe mode

Help

FAQ

Is Base64 encryption?Show
No. Base64 is an encoding, not encryption. Anyone can decode it back to the original data.
Why does decoding fail?Show
Check if the string contains invalid characters, or if the length is not a multiple of 4.
What is URL-safe mode?Show
URL-safe mode replaces + with -, / with _, and removes trailing =, making it safe for URLs.
Why does my decoded text look like gibberish?Show
That usually means the Base64 content represents binary data (e.g., images, compressed files), not UTF-8 text. Save the decoded bytes as a file instead of displaying as text.

Quick Start

  1. Select encode or decode mode
  2. Enter text or Base64 string
  3. Result displays in real-time, click to copy
  4. For URL usage, enable URL-safe mode

Privacy Notice

Full guide

What is Base64?

Base64 is a binary-to-text encoding. It converts bytes (binary data) into a limited set of readable ASCII characters:

  • A-Z, a-z, 0-9, +, / (and = padding)

Because the output is plain text, Base64 is often used in places where you can only safely transmit text, for example:

  • JSON / XML payloads
  • URLs (usually with Base64URL variant)
  • Email (MIME)
  • Embedding small files in text formats

What this tool does

On the Base64 page (/en/base64) you can:

  • Encode text into Base64
  • Decode Base64 back into text
  • Quickly verify whether a string looks like Base64

How to use (examples)

Encode a string

Input:

hello world

Output (Base64):

aGVsbG8gd29ybGQ=

Decode a Base64 string

Input:

aGVsbG8gd29ybGQ=

Output:

hello world

Common pitfalls

1) Base64 is not encryption

Base64 does not protect your data. It only changes representation.

If you need confidentiality, use real encryption (e.g. AES-GCM) and keep keys secure.

2) Padding and newlines

  • Many Base64 strings end with = or ==.
  • Some systems insert line breaks every 76 characters (email/MIME). You may need to remove whitespace before decoding.

3) Base64 vs Base64URL

When you put Base64 into URLs, + and / may be problematic.

Base64URL typically:

  • Replaces + with -
  • Replaces / with _
  • Removes = padding

If you see those characters, the input may be Base64URL rather than standard Base64.

Privacy & security

  • This tool is designed to run client-side (in your browser).
  • Your input should not be uploaded.

Even so:

  • Avoid pasting passwords, private keys, or personal data on public/shared computers.
  • If the data is highly sensitive, prefer offline tools.