Base64 Decoder

Decode Base64 encoded text back to its original format.

Base64 Input
Paste Base64 text to decode
Decoded Output
Original text

What is Base64 Decoding?

Base64 decoding converts Base64-encoded ASCII text back to its original binary format. It reverses the encoding process to retrieve the original data.

Key Features

  • Reversible: Converts Base64 back to original data
  • Lossless: No data is lost in the process
  • Error Detection: Invalid Base64 will produce an error
  • Fast: Quick conversion process

How It Works

  1. Base64 characters are mapped back to 6-bit values
  2. Values are combined into original bytes
  3. Padding (=) is removed
  4. Original data is reconstructed

Common Use Cases

  • Reading Data URIs: Extract embedded images from HTML/CSS
  • API Responses: Decode Base64-encoded API data
  • Email Attachments: Decode MIME email attachments
  • JWT Tokens: Decode JSON Web Token payloads
  • File Transfer: Decode transmitted files

Example

Base64 Input: SGVsbG8sIFdvcmxkIQ== Decoded: Hello, World!

The decoder automatically handles padding and validates the input.

Invalid Input

If the input is not valid Base64, you'll get an error. Valid Base64 only contains:

  • Letters: A-Z, a-z
  • Numbers: 0-9
  • Symbols: +, /, =