Question 1

What is Base64 encoding?

Accepted Answer

Base64 is a binary-to-text encoding scheme that converts binary data into ASCII characters using 64 symbols: A-Z, a-z, 0-9, plus + and /. It's used when binary data needs to be stored or transmitted over media designed for text, like email or JSON APIs.

Question 2

What is URL-safe Base64?

Accepted Answer

URL-safe Base64 replaces + with - and / with _, removing characters that have special meaning in URLs. It also removes trailing = padding. Used in JWT tokens, data URLs, and anywhere Base64 appears in URL paths or query parameters.

Question 3

How do I use Base64 for HTTP Basic Auth?

Accepted Answer

Basic Auth encodes username:password as Base64. The header format is: Authorization: Basic base64(username:password). For user:pass, encode 'user:pass' to get 'dXNlcjpwYXNz'. Note: Base64 is NOT encryption - use HTTPS to protect credentials in transit.

Question 4

Why does Base64 output grow by 33%?

Accepted Answer

Base64 encodes 3 bytes into 4 characters. Every 3 input bytes become 4 output bytes, a 4/3 ratio or 33% increase. For example, 12 bytes encode to 16 characters. This overhead is the tradeoff for having only safe ASCII characters in the output.

Question 5

Is Base64 secure encryption?

Accepted Answer

NO. Base64 is encoding, not encryption. Anyone can decode Base64 back to original text. It provides zero security - it's just a representation format. Never use Base64 to protect secrets. Use proper encryption (AES, RSA) for security, then optionally Base64 encode the encrypted output.

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