What is Base64?
Base64 is an encoding method that converts binary data (images, files, bytes) into a text string made of 64 safe ASCII characters (A-Z, a-z, 0-9, +, /). It doesn't encrypt data — it just changes the representation, making binary data safe to include in text-based formats.
When is Base64 Used?
- Email attachments: MIME uses Base64 to embed binary files in email messages.
- Inline images in HTML/CSS:
<img src="data:image/png;base64,..."> - JWT tokens: JSON Web Tokens use Base64URL encoding for the header and payload.
- API authentication: HTTP Basic Auth encodes credentials as Base64.
- Data URIs: Storing fonts, icons, or images directly in CSS files.
Base64 vs Base64URL
- Standard Base64: Uses
+and/characters — not URL-safe. - Base64URL: Replaces
+with-and/with_— safe for use in URLs and JWT tokens.
How to Encode Text to Base64 Online
1Open the Base64 Encoder / Decoder tool.
2Choose mode: Encode (text → Base64) or Decode (Base64 → text).
3Paste your input — the output updates instantly.
4Copy the result with one click.
💡 Security Note: Base64 is NOT encryption. Anyone can decode a Base64 string without a key. Never use Base64 to hide sensitive data — use proper encryption (AES, RSA) instead.
FAQ
How much bigger is Base64 encoded data?
Base64 encoding increases data size by approximately 33%. This is why inline Base64 images in CSS should only be used for small images — large images should remain as external files.
Why does Base64 end with = signs?
The = character is a padding character. Base64 encodes 3 bytes into 4 characters, so if the input isn't divisible by 3, it pads with one or two = signs.