Base64 is an encoding scheme that converts binary data into a text string using 64 printable ASCII characters. It is everywhere in web development — email attachments, embedding images in CSS, JWT tokens, API authentication headers, and data URLs.
When Do You Need Base64?
- API authentication — Basic Auth headers encode username:password as Base64
- JWT tokens — JSON Web Tokens use Base64url encoding for their payload
- Embedding images — CSS and HTML can include small images as Base64 data URLs to avoid HTTP requests
- Email attachments — MIME email attachments use Base64 encoding
- Storing binary in JSON — JSON cannot contain binary data, so images/files are Base64 encoded first
Base64 vs Encryption
Base64 is encoding, not encryption. Anyone can decode a Base64 string instantly — it provides no security. Never use Base64 to “hide” passwords or sensitive data. Use proper encryption (AES, RSA) for security. Base64 exists purely for compatibility — to represent binary data as text.
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