Base64 is specifically designed for binary data, while other encodings like UTF-8 are for text. Base64 ensures data survives transport through systems that might interpret certain bytes as control characters. It's also more efficient than hexadecimal for encoding binary data.

Base64 converts every 3 bytes (24 bits) of binary data into 4 ASCII characters. Since each ASCII character is typically stored as 1 byte (8 bits), this results in 4 bytes for every 3 bytes of original data - a 33% increase in size. The = padding characters can add additional bytes.

Use URL-safe Base64 when encoding data that will be used in URLs or filenames. Standard Base64 uses + and / characters which have special meaning in URLs and need to be percent-encoded. URL-safe Base64 replaces these with - and _ which don't require encoding.

A valid Base64 string should only contain characters from the Base64 alphabet (A-Z, a-z, 0-9, +, /, = for standard; A-Z, a-z, 0-9, -, _ for URL-safe). The length should be a multiple of 4, and padding (=) should only appear at the end. Our tool includes comprehensive validation.