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base64 2025-01-19

Understanding Base64 Encoding and Decoding

A comprehensive guide to Base64 encoding, its uses, and how it works.

Base64 is a binary-to-text encoding scheme that represents binary data in an ASCII string format.

Why Base64?

Base64 encoding is essential when you need to:

  • Transmit binary data over text-based protocols
  • Embed images in HTML or CSS
  • Store binary data in JSON or XML
  • Send attachments in emails

How Base64 Works

Base64 converts binary data into a set of 64 printable ASCII characters:

  • A-Z (26 characters)
  • a-z (26 characters)
  • 0-9 (10 characters)
  • + and / (2 characters)
  • = for padding

Encoding Process

1. Take the binary data

2. Split into 6-bit groups

3. Map each group to a Base64 character

4. Add padding if necessary

Common Use Cases

Data URLs: Embed small images directly in HTML


API Authentication: Basic authentication headers use Base64

Authorization: Basic dXNlcm5hbWU6cGFzc3dvcmQ=

Important Notes

  • Base64 is NOT encryption - it's just encoding
  • Encoded data is about 33% larger than original
  • URL-safe Base64 uses - and _ instead of + and /

Use our Base64 tool to easily encode and decode your data.