Base64 与 Hex 编码：什么时候用哪一个

Base64 and hex are both ways to show binary bytes as printable text, yet they get chosen for very different jobs. Picking the wrong one costs you bandwidth, log readability or debugging time. Here is the practical difference.

The size question

Hex maps every byte to exactly two characters, so output is always twice the input size. Base64 packs 3 bytes into 4 characters, which is about 33 percent overhead. When encoding kilobytes of payload into a URL or a JSON field, that difference adds up fast.

The readability question

Hex wins when humans inspect data: every two characters are one byte, offsets align, and byte patterns are easy to spot in logs or git binaries. Base64 wins when machines transport data, because the payload is shorter and URL-safe variants exist.

Where each one shows up daily

• JWTs use URL-safe Base64 for header, payload and signature — decode any token with the JWT Decoder.
• Data URLs embed small images as base64 directly into HTML or CSS.
• Commit diffs and checksum output print bytes as hex — inspect any string the same way with the Hex to Text Converter.
• Email (MIME) standardized Base64 for attachments decades ago.

Quick decision table

Situation	Pick
Embed binary inside JSON, XML or a URL	Base64 (URL-safe for URLs)
Human wants byte-level inspection	Hex
Bandwidth matters, text channel required	Base64
Comparing hashes or binary fingerprints	Hex

Try both sides live: the Base64 Encoder & Decoder and the Hex Converter run entirely in your browser — handy when a UTF-8 multibyte character makes both outputs confusing at a glance.