Encodings / RFC 4648
Base64 Decoder
Decode standard or URL-safe Base64 without silently accepting malformed input.
Whitespace may be ignored. URL-safe input may use hyphen and underscore.
Ready.
Practical notes
What this decoder checks
Base64 represents each three input bytes with four printable characters. Padding is validated and missing terminal padding is restored only when the remaining length is unambiguous.
UTF-8 mode rejects invalid byte sequences instead of inserting replacement characters. Hex mode is useful for arbitrary binary data. Base64 is an encoding, not encryption.