UUID Validator & Decoder
指导
UUID Validator & Decoder
Paste any UUID and instantly see whether it is valid, which version it follows (v1 through v8, plus the special Nil and Max UUIDs), and what metadata is hidden inside its bits. The tool decodes v1, v6, and v7 timestamps to a human-readable date, extracts the node ID / MAC fragment from time-based UUIDs, and reports the variant exactly as defined by RFC 4122 and RFC 9562. Paste a single UUID for full details, or one UUID per line to validate a whole batch at once.
如何使用
- Paste a UUID into the input box. For batch validation, enter one UUID per line.
- The summary box shows whether the input is valid and which version it uses.
- The Decoded Details table breaks down every field of the first UUID, including timestamps and node IDs where applicable.
- The Batch Results table appears when more than one UUID is provided so you can scan a whole list at a glance.
- 点击 尝试一个示例 to load a mix of v1, v3, v4, v7, and Nil UUIDs to see how each version is decoded.
特征
- Full RFC coverage – Detects UUID versions v1 through v8 plus Nil and Max UUIDs as defined in RFC 4122 and RFC 9562.
- Timestamp decoding – Converts v1 and v6 100-nanosecond Gregorian timestamps and v7 millisecond Unix timestamps to ISO and UTC dates.
- Node ID inspection – Pulls the 48-bit node field, formats it like a MAC address, and flags multicast or locally administered addresses.
- Variant detection – Reports the UUID variant (RFC 4122, NCS, Microsoft, or future) from the variant bits.
- 批量模式 – Validate dozens of UUIDs at once with a clean per-row verdict, version, and notes.
- 100% 客户端 – Bit-level parsing runs in your browser. Nothing is sent to a server, so private identifiers never leave your machine.
常问问题
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What is a UUID and how is it structured?
A UUID (Universally Unique Identifier) is a 128-bit value usually written as 32 hexadecimal characters in the canonical 8-4-4-4-12 form. The 128 bits are split into well-defined fields: a time / random portion, a 4-bit version field that identifies how the UUID was generated, a 2- or 3-bit variant field that identifies which UUID specification the value follows, and remaining bits that may carry a clock sequence, node ID, or random data depending on the version.
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What is the difference between UUID v1, v4, and v7?
UUID v1 encodes the current time (in 100-nanosecond intervals since 1582-10-15) plus a node ID derived from a MAC address, which makes it sortable by time but reveals the host that generated it. UUID v4 is almost entirely random — 122 random bits with 6 fixed bits for version and variant — so it is unpredictable but not sortable. UUID v7, defined in RFC 9562, takes the best of both: the first 48 bits are a Unix millisecond timestamp followed by random bits, giving you values that are time-sortable, indexable, and still unguessable.
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What is the UUID variant field and why does it matter?
The variant field is a small group of high bits inside the 9th byte of the UUID. It tells parsers which UUID specification the value conforms to: NCS backwards compatibility (top bit 0), the modern RFC 4122 / RFC 9562 layout (top bits 10), Microsoft's legacy GUID layout (top bits 110), or reserved for future use (top bits 111). Decoders must read the variant before the version, because the position of the version nibble is only meaningful for RFC 4122-style variants.
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Are the Nil UUID and Max UUID actually valid?
Yes. The Nil UUID (00000000-0000-0000-0000-000000000000) is defined in RFC 4122 §4.1.7 as a special, all-zero UUID that is used to represent an unknown or empty value. The Max UUID (ffffffff-ffff-ffff-ffff-ffffffffffff) was added in RFC 9562 §5.10 as the all-ones counterpart, often used as a sentinel upper bound in databases. Both are syntactically valid UUIDs but do not carry any decoded fields like a timestamp or node ID.
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Can a v3 or v5 UUID be reversed back to its original name?
No. UUID v3 and v5 are name-based: the implementation hashes a namespace UUID together with an input name using MD5 (v3) or SHA-1 (v5) and uses the resulting digest, with the version and variant bits overwritten, as the UUID. Because cryptographic hash functions are designed to be one-way, you cannot recover the original namespace and name from the resulting UUID — you can only verify that a candidate name plus a known namespace produces the same UUID.
