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UUID Validator & Decoder

Validate UUIDs and GUIDs in bulk and decode each one: version, variant, and the embedded timestamp of v1, v6 and v7 UUIDs, with canonical and URN forms.

Overview

Validates UUIDs and GUIDs, one or thousands at a time, and decodes each valid one: its version, its variant, and for version 1, 6 and 7 the timestamp it was created at. It accepts braces, urn:uuid: prefixes, upper case and the 32-digit form without hyphens, and outputs every common format. Everything runs in your browser.

How It Works

Paste UUIDs one per line. Counters show how many are valid, invalid or non-standard, with a breakdown by version. The first valid UUID is decoded in detail, with its canonical, upper-case, GUID-with-braces, URN, base64 and 128-bit integer forms, each with a copy button. A table lists every line with its result, version and timestamp or error, and the whole table can be copied or downloaded as CSV.

Step-by-Step Usage Guide

  1. Paste one UUID or a list, one per line.
  2. Check the valid, invalid and non-standard counters.
  3. Read the version, variant and timestamp of the decoded UUID.
  4. Copy the format you need, such as braces for .NET or URN for XML.
  5. Download the CSV to keep a record of every line's result.

Technical Specifications & Standards

RFC 9562, which replaced RFC 4122 in 2024, defines UUID versions 1 to 8 and the nil and max UUIDs. The version is the first hex digit of the third group and the variant is the top bits of the fourth group; only variant 10xx is the RFC layout, so other variants are reported as NCS, Microsoft or reserved and counted as non-standard. Version 1 stores a 60-bit count of 100-nanosecond intervals since 15 October 1582 split across three fields, plus a clock sequence and a 48-bit node. Version 6 stores the same timestamp in sortable order. Version 7 starts with a 48-bit Unix timestamp in milliseconds, which is why v7 keys sort by creation time in databases. The decoder rebuilds these timestamps exactly and shows them in ISO 8601 UTC. For v1 and v6 it reads the node and says whether the multicast bit marks it as random rather than a MAC address. Versions 3 and 5 are name-based hashes, so their input name cannot be recovered, and version 4 carries only random bits.

Targeted Use Cases

  • Finding out when a v7 or v1 primary key was generated while debugging a database row.
  • Validating a CSV column of IDs before importing it into a system that rejects bad UUIDs.
  • Checking whether a library actually produces version 4 or version 7 UUIDs.
  • Converting a GUID from a Windows registry key into canonical lower-case form.

Notes & Gotchas

  • Use version 7 for new database keys when you want time-ordered inserts.
  • Remember that v1 UUIDs can reveal a creation time and possibly a machine MAC address.
  • Store UUIDs in lower-case canonical form so string comparisons stay consistent.

Frequently Asked Questions

How do I get the timestamp from a UUID?

Paste it here. Version 1 and 6 UUIDs hold a 100-nanosecond timestamp since 1582 and version 7 holds Unix milliseconds; the decoder converts either to an ISO 8601 date. Version 4 has no timestamp at all.

What is the difference between a UUID and a GUID?

They are the same 128-bit identifier. GUID is Microsoft's name and is often written in upper case inside braces. The validator accepts both spellings and outputs both.

Why is my UUID marked non-standard?

Its variant bits are not the RFC 9562 layout, or its version digit is 0 or above 8. The string is still 128 bits of valid hex, but RFC parsers may reject it or misread its version.

Can I recover the name from a v3 or v5 UUID?

No. Versions 3 and 5 are MD5 and SHA-1 hashes of a namespace and name. The same inputs always give the same UUID, but the name cannot be read back out of it.

Is there a limit on how many UUIDs I can check?

The validator processes up to 2,000 lines at a time, which keeps the page responsive. Split larger lists into batches.

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