Base64 to UUID Converter

Convert Base64 bytes into a UUID only when the decoded payload is exactly 16 bytes.

Base64 or Base64URL payload

ReadyOnly payloads decoding to exactly 16 bytes are accepted.

Base64 to UUID: Canonical Round-Trip Check

Inspect the decoded 16 bytes, UUID version/variant and canonical Base64/Base64URL re-encodings to verify a lossless round trip.

Position quick-win audit

Strict Base64 UUID decoding

A UUID payload must be 16 bytes: 24 characters with == padding or 22 without padding. v268 rejects mixed alphabets, malformed padding, wrong decoded lengths, and non-zero unused pad bits instead of accepting whatever atob can decode.

RFC 9562 boundary

UUIDs are 128-bit values. Version meaning is interpreted only inside the appropriate variant, and representation conversion never changes the underlying 16 bytes.

UUID transport checks

A UUID payload must decode to exactly 16 bytes

Base64 and Base64URL can represent arbitrary byte lengths. The converter should only accept a UUID when the decoded payload is exactly 128 bits; padding style does not change that requirement.

Preserve byte order across systems

Some platforms serialize GUID fields with mixed-endian conventions while canonical UUID text is network-order hexadecimal. If another system produces a different textual UUID from the same 16 bytes, check its GUID byte-order convention before assuming the data is corrupted.

Round-trip the exact transport form

After decoding, encode the UUID bytes back to the expected Base64 or Base64URL form and compare normalized padding. A round trip catches accidental text encoding, truncation, or byte-order changes that a visually valid UUID string can hide.