Base64 Encoding Guide

Encode and decode Base64 strings with our free online tool.

Introduction

Base64 encoding converts binary data to ASCII text format. It's used for:

• Embedding images in HTML/CSS
• Encoding data in URLs
• Email attachments (MIME)
• API data transfer
• Storing binary data in JSON

How to Use

Encoding

1. Go to Base64 Encoder/Decoder
2. Select Encode mode
3. Enter your text or data
4. Copy the Base64 output

Decoding

1. Select Decode mode
2. Paste the Base64 string
3. View the decoded output

How Base64 Works

Base64 uses 64 characters:

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

Every 3 bytes of input become 4 Base64 characters.

Common Use Cases

Embedding Images

Convert small images to Base64 for inline CSS/HTML:

.icon {
  background: url('data:image/png;base64,iVBORw0K...');
}

API Authentication

Encode credentials for Basic Auth:

const auth = btoa(`${username}:${password}`);
// Use in header: `Basic ${auth}`

Data URLs

Include small files directly in web pages:

<img src="data:image/png;base64,iVBORw0KGgo..." />

Best Practices

When to Use

• Small images (<10KB)
• Configuration data
• Simple authentication
• Embedding in JSON/XML

When NOT to Use

• Large files (increases size by 33%)
• Performance-critical applications
• Files served separately
• Already compressed data

Security Notes

• Base64 is NOT encryption
• Anyone can decode Base64
• Don't use for passwords alone
• Combine with actual encryption

Related Tools

• Image to Base64 - Convert images
• URL Encoder - URL-safe encoding