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UUID v7 Generator

Create time-ordered version 7 UUIDs and see the timestamp inside each one. Useful for database keys, event IDs and anywhere sortable identifiers help.

1 to 1,000.

Output format

xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx

Choose your options and press Generate. Identifiers are created in your browser.

How a UUID v7 Is Built

RFC 9562 defines v7 as a 48-bit big-endian Unix timestamp in milliseconds, followed by the version (7), 12 bits called rand_a, the variant, and 62 bits called rand_b (RFC 9562 §5.7 (opens in a new tab)). Implementations may use part of the random space for a sub-millisecond fraction or a counter, so that IDs created in the same millisecond still sort in order.

UUID v7 bit layout
FieldBitsContents
unix_ts_ms48Milliseconds since 1970-01-01 UTC
ver4Always 7
rand_a12Random data, or extra clock precision/counter
var2Always binary 10
rand_b62Random data, optionally with a counter

The generator on this page uses the uuid library, which keeps its output in order within a session: a batch of 1,000 v7 UUIDs comes out already sorted, which the tool’s automated tests check.

Why Sortable UUIDs Help Databases

With random UUIDs, each new key lands at an unpredictable point in a B-tree index, touching many pages. Time-ordered keys cluster new rows together. RFC 9562 states that the real-world difference in index locality can be an order of magnitude or more (RFC 9562 §6.11 (opens in a new tab)). Your results depend on your database engine, storage format and workload, so test with realistic data.

The RFC also recommends storing UUIDs as 128-bit binary values rather than 36-character text where the database supports it (RFC 9562 §6.13 (opens in a new tab)). If you use .NET with SQL Server, check how GUIDs are converted to bytes, since Microsoft’s storage layout differs from the RFC’s big-endian order.

UUID v7 Caveats

  • Ordering is approximate across systems. Each machine’s clock decides its timestamps, and clocks drift or get corrected.
  • The time is visible. Anyone with the ID can see roughly when it was generated.
  • The timestamp isn’t an audit record. It shows the generator’s clock, not when data was saved.
  • Fewer random bits than v4. 74 versus 122, still plenty for uniqueness in typical use.

To inspect an existing v7 ID, paste it into the UUID decoder. If you don’t need ordering, the UUID v4 generator reveals nothing about creation time.

UUID v7 in Code

C#.NET 9 or later
Guid id = Guid.CreateVersion7();
PythonPython 3.14 or later
import uuid
u = uuid.uuid7()
print(u, u.time)  # u.time = milliseconds since the Unix epoch
SQLPostgreSQL 18 or later
SELECT uuidv7();
SELECT uuid_extract_timestamp(uuidv7());
JavaScriptnpm install uuid
import { v7 as uuidv7 } from 'uuid';
const id = uuidv7();

Sources: Microsoft Learn (opens in a new tab), Python docs (opens in a new tab), PostgreSQL docs (opens in a new tab), uuid package (opens in a new tab). For every version in one place, use the online GUID generator.

Frequently Asked Questions

What is UUID v7?

A UUID version defined in RFC 9562 whose first 48 bits are a Unix timestamp in milliseconds, followed by the version, variant and 74 bits of random data or counter. Values created later generally sort after earlier ones.

Are UUID v7 values strictly ordered?

Not universally. A single generator can keep its own output in order, but IDs from different machines depend on their clocks, and IDs created in the same millisecond on different systems can interleave. Clocks can also move backwards.

Can I get the creation time from a UUID v7?

You can read the embedded millisecond timestamp, as this page and the UUID decoder do. It reflects the generating clock, so treat it as approximate and don’t rely on it as proof of when a record was created.

Is UUID v7 good for database primary keys?

Often, yes. Its time ordering keeps new keys near each other in B-tree indexes, which RFC 9562 notes can significantly improve insert performance compared with random UUIDs. Measure with your own database and workload.

Does UUID v7 reveal private information?

It reveals approximately when the ID was generated. If that matters, for example in public URLs, consider UUID v4 instead.

How do I generate UUID v7 in my language?

In .NET 9+, Guid.CreateVersion7(); in Python 3.14+, uuid.uuid7(); in PostgreSQL 18+, uuidv7(); in JavaScript, the uuid package’s v7().

Sources