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Base64 format rules

Binary-to-text encoding for bytes, data URLs, and credentials.

Format rules

  • Uses A-Z a-z 0-9 + /
  • Padding uses =
  • Base64URL swaps +/ for -_

Valid example

SGVsbG8=

Invalid example

SGVsbG8

Common errors

  • Assuming Base64 accepts syntax from a similar format
  • Using the wrong encoding or line ending
  • Copying invisible characters from rich text
  • Testing only the happy path and not parser errors

Online validation and conversion

Compared with nearby formats

Base64 should be chosen for the parser and ecosystem that will consume it. Prefer strict formats for APIs, human-friendly formats for ops config, and signed formats only when verification is required.