How do I tell which version a UUID is?

Read the 13th hexadecimal character, which is the first digit of the third group. In 0190b5c2-3a40-7000-8000-000000000000 that digit is 7, so it is a v7. In 0190ae99-a800-4000-8000-000000000000 it is 4, a v4. The same spot reads 1, 3 or 5 for those versions. Paste the UUID here and the version is read off that exact nibble for you.

Where are the version nibble and the variant bits?

The version nibble is the high 4 bits of byte 6, which is the 13th hex character (group three, first digit). The variant lives in the top bits of byte 8, the 17th hex character (group four, first digit). A value of 8, 9, a or b there means the RFC 4122/9562 variant; c or d means a Microsoft GUID; 0 through 7 means the legacy NCS layout. This tool shows both characters under the breakdown.

Can I recover the time a UUID was created?

Only for v1 and v7. A v1 stores a 60-bit count of 100-nanosecond ticks since 1582-10-15, so c232ab00-9414-11ec-b3c8-9e6bdeced846 decodes to 2022-02-22T19:22:22Z. A v7 stores a 48-bit Unix-millisecond timestamp in its first six bytes. A v4 is pure random and a v5 is a hash, so neither holds any creation time to recover, and the tool says so.

What does a v4 UUID tell me?

Almost nothing beyond that it is random. A v4 fixes only the version nibble (4) and the variant bits (10xx); the other 122 bits come from a cryptographic random source. So you can confirm it is a valid v4 and that it follows the RFC variant, but there is no embedded timestamp, machine address or counter. If you need ordering or a recoverable time, that is exactly what v7 was designed for.

What are the Nil and Max UUIDs?

The Nil UUID is all zeros, 00000000-0000-0000-0000-000000000000, used as an empty placeholder the way null is used elsewhere. The Max UUID is all ones in hex, ffffffff-ffff-ffff-ffff-ffffffffffff, defined by RFC 9562 as the largest possible value, handy as an upper bound in range scans. Both are valid but carry no version or variant meaning, so the tool flags them separately.

Does case or missing hyphens matter?

No. The inspector trims whitespace, lowercases the input and accepts either the hyphenated 8-4-4-4-12 form or a bare 32-character hex string, so C232AB00-9414-11EC-B3C8-9E6BDECED846 and c232ab009414 11ec b3c8 9e6bdeced846 with hyphens removed decode identically. Anything that is not 32 valid hex digits in that shape is reported as invalid rather than guessed at.

Figure out what kind of ID a system is handing you

A new service drops UUIDs into its API responses and the docs never say which flavour. Paste one here and the version digit tells you immediately: a 7 means time-ordered keys you can sort, a 4 means pure random, a 1 means there is a MAC address and a creation time hiding inside. Now you know whether sorting by ID is meaningful and whether the IDs leak when or where they were minted.

Recover the creation time from a v1 or v7 UUID

A log line references a record only by its UUID and you need to know when it was created. If it is a v1 or v7, the timestamp is in the bytes. Paste it, read the UTC and local time straight off, and you have your answer without touching the database. The v1 path also surfaces the node, which can pin the originating machine.

Confirm a UUID is the version your schema expects

Your column comment says "v7 only, for index locality" but a teammate pasted what might be a v4. Drop it in: if the version reads 4, you have caught a bug before it scatters writes across the B-tree. The variant check catches the rarer case of a Microsoft GUID that slipped in from a .NET service expecting little-endian byte order.

Teach or learn the UUID byte layout

Reading RFC 9562 is dry; seeing it is fast. Paste a real UUID and the field breakdown lights up time_low, time_mid, the version nibble and the variant bits in their actual positions, so the spec stops being abstract. It is a quick way to explain to a teammate exactly why the 13th character decides the version.

UUID Inspector — Detect Version, Variant and Timestamp

Paste a UUID, read back its version, variant and the timestamp baked into the bytes

Runs locally
Category Developer & DevOps
Best for Formatting, validating, shrinking, or inspecting code-adjacent text.

Paste any UUID and this reads back the version digit (13th hex char), the variant bits (17th hex char), and — for v1 and v7 — the timestamp baked into the bytes. v4 is pure random, so it has no time to recover.

Paste a UUID

Paste any UUID above to see its version, variant and embedded timestamp.

What this tool does

Free UUID inspector that decodes any UUID you paste. It reads the version digit (the 13th hex character) and the variant bits (the 17th) straight out of the canonical 8-4-4-4-12 string, so you instantly know whether you are holding a v1, v3, v4, v5, v7 or v8 identifier and whether it follows the RFC 4122/9562 layout, the Microsoft GUID layout or the legacy NCS one. For the time-based versions it goes further: a v1 UUID hides a 60-bit count of 100-nanosecond intervals since 1582-10-15, which this tool converts to a real UTC instant along with the 14-bit clock sequence and the 48-bit node (historically the MAC address); a v7 UUID carries a 48-bit Unix-millisecond timestamp in its leading bytes, decoded to UTC and your local time. It also lays out every hex field and special-cases the Nil and Max sentinels. Everything runs in your browser, with one-click copy of the full analysis and a shareable link. 100% client-side, nothing is uploaded.

Tool details

Input: Numbers; The page exposes text boxes, numeric controls, file pickers, or structured inputs depending on the tool.
Output: Live result + Copy; The result area focuses on usable output, with copy, download, or preview actions when supported.
Privacy: Browser-side processing; The main tool logic does not call an external API, so inputs normally stay in the current tab.
Save / share: Shareable URL state; Key settings are encoded in the URL so another person can reopen the same setup.
Performance budget: Initial JS <= 9 KB; No WASM budget is declared, keeping the tool quick to open on mobile.
Best fit: Developer & DevOps · Developer; Category and role tags drive related tools, internal links, and quick fit checks.

How to use

1. Input

Paste or drop your content into the tool panel.
2. Process

Click the button. All processing is local in your browser.
3. Copy / Download

Copy the result or download to disk in one click.

How UUID Inspector fits into your work

Use it in the small gaps between coding, reviewing, debugging, and shipping.

Developer jobs

Formatting, validating, shrinking, or inspecting code-adjacent text.
Preparing snippets for documentation, tickets, commits, or handoff.
Checking a small payload quickly without switching tools.

Developer checks

Run irreversible transforms like minify or obfuscate on a copy.
Keep secrets out of pasted snippets unless the tool explicitly stays local.
Use your normal tests or linter before shipping transformed code.

Good next steps

These links move the current task into a more complete workflow.

Real-world use cases

Figure out what kind of ID a system is handing you
A new service drops UUIDs into its API responses and the docs never say which flavour. Paste one here and the version digit tells you immediately: a 7 means time-ordered keys you can sort, a 4 means pure random, a 1 means there is a MAC address and a creation time hiding inside. Now you know whether sorting by ID is meaningful and whether the IDs leak when or where they were minted.
Recover the creation time from a v1 or v7 UUID
A log line references a record only by its UUID and you need to know when it was created. If it is a v1 or v7, the timestamp is in the bytes. Paste it, read the UTC and local time straight off, and you have your answer without touching the database. The v1 path also surfaces the node, which can pin the originating machine.
Confirm a UUID is the version your schema expects
Your column comment says "v7 only, for index locality" but a teammate pasted what might be a v4. Drop it in: if the version reads 4, you have caught a bug before it scatters writes across the B-tree. The variant check catches the rarer case of a Microsoft GUID that slipped in from a .NET service expecting little-endian byte order.
Teach or learn the UUID byte layout
Reading RFC 9562 is dry; seeing it is fast. Paste a real UUID and the field breakdown lights up time_low, time_mid, the version nibble and the variant bits in their actual positions, so the spec stops being abstract. It is a quick way to explain to a teammate exactly why the 13th character decides the version.

Common pitfalls

Reading the wrong digit for the version. The version is the 13th hex character (third group, first digit), not the first character of the whole string. The leading bytes of a v7 are a timestamp, so they vary; only that one nibble is fixed to the version number.
Expecting a timestamp from a v4. A v4 is 122 bits of randomness with only the version and variant fixed, so there is no creation time, machine or counter to recover. If you need a recoverable time, generate v7 instead and the leading 48 bits give it back.
Treating the variant as the version. The variant bits (17th hex character, values 8/9/a/b for RFC) describe the byte-order family, not the generation algorithm. A v4 and a v7 can share the same variant; the version nibble is what separates them.

Privacy

Every step of the analysis — version and variant decoding, the v1 and v7 timestamp math, the hex field breakdown — is plain JavaScript that runs in your browser tab. The UUID you paste never leaves the page and is not logged anywhere. The one caveat: the shareable link encodes the UUID in the query string, so a link pasted into chat will record that UUID in the recipient server's access log. A UUID is an identifier rather than a secret, but if it maps to something sensitive, use the copy button and paste the text instead of sharing the URL.

FAQ

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UUID Inspector — Detect Version, Variant and Timestamp

What this tool does

Tool details

How to use

1. Input

2. Process

3. Copy / Download

How UUID Inspector fits into your work

Developer jobs

Developer checks

Good next steps

Real-world use cases

Figure out what kind of ID a system is handing you

Recover the creation time from a v1 or v7 UUID

Confirm a UUID is the version your schema expects

Teach or learn the UUID byte layout

Common pitfalls

Privacy

FAQ

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