Веб-Стандарт и Спецификация RFC

Base64 vs Base64URL — Ключевые отличия

Base64 vs Base64URL объяснено. Символы, padding, когда использовать (JWT, OAuth, URL). RFC 4648 §4 vs §5.

Почему стандартный Base64 не подходить для URL

Standard Base64 (RFC 4648 §4) uses the 64-character alphabet A-Z, a-z, 0-9, +, /, with = used as trailing byte padding.

However, when standard Base64 strings are passed in HTTP query parameters, URI path segments, or web cookies:

  • The plus sign + is automatically interpreted by web servers as a space character (%20), corrupting the payload.
  • The forward slash / is interpreted by web routers as a path delimiter, altering URL routing logic.
  • The equals sign = is used as a key-value parameter separator in query strings.

Замена символов алфавита (RFC 4648 §5)

FeatureStandard Base64Base64URL (URL-Safe)
Index 62+ (plus)- (hyphen)
Index 63/ (slash)_ (underscore)
Padding Character (=)Mandatory (Length % 4 == 0)Omitted or Unpadded

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