UUID v1 Generator (Timestamp-Based)

Generate RFC 4122 version 1 UUIDs: Gregorian 100-ns timestamp plus random node ID. For legacy systems, Cassandra TIMEUUIDs, and older Windows COM code.

uuid

guid

unique id

generator

developer

RFC 4122

Generate:UUID(s)

Click Generate to create UUIDs

Gregorian timestamp + random node. Reveals generation time.

About UUID v1

UUID version 1 encodes a 60-bit Gregorian timestamp — 100-nanosecond intervals since 1582-10-15 UTC — plus a 14-bit clock sequence and a 48-bit node identifier. Originally the node was the network interface's MAC address, which leaked the generating machine. This generator uses a random node ID with the multicast bit set, which RFC 4122 §4.5 explicitly allows as a privacy-preserving substitute for a real MAC. Browsers can't access hardware MACs anyway. v1 is mostly a legacy format today. The timestamp reveals when the UUID was generated (to within 100 ns), which is a privacy problem for public-facing IDs. v7 solves the same sortability problem with a cleaner format, better entropy, and no MAC-derived fields. Use v1 only when interoperating with a system that explicitly requires it: Cassandra's TIMEUUID column (which orders v1s chronologically for range queries), older Java UUIDs emitted by JUG, legacy Windows COM code, and some enterprise messaging systems that embed v1 in wire protocols. The 13th character is always 1 (version nibble), the 17th is 8, 9, a, or b (variant). The timestamp fields are laid out high-bits-last across the first three hyphen-separated groups — an endianness quirk that catches every developer the first time they try to parse a v1 by hand. Output is lowercase and hyphenated per the RFC.

Features

Generate cryptographically random UUID v4 identifiers
Create single or bulk UUIDs at once
Copy individual or all UUIDs to clipboard
Compliant with RFC 4122 standard

How to Use

Click "Generate" to create a new UUID
Set the quantity for bulk generation
Click any UUID to copy it to your clipboard
Use the generated UUIDs in your applications

Frequently Asked Questions

Why does UUID v1 leak information?

The timestamp reveals when the UUID was generated (to within 100 ns), and the original node field was the machine's MAC address — identifying the specific computer. Modern browsers and implementations use a random node with the multicast bit set, but the timestamp leak is inherent to v1 and can't be hidden.

Should I use v1 in new projects?

No. For time-ordered UUIDs use v7 — same sortability benefit, no timestamp leak, cleaner spec. For random opaque IDs use v4. v1 exists today almost entirely for interoperability with older systems: Cassandra TIMEUUIDs, legacy Java UUID code, old Windows COM registrations.

Does this generator use my real MAC address?

No — browsers don't expose hardware MAC addresses for privacy reasons. This generator creates a random 48-bit node with the multicast bit set, which RFC 4122 §4.5 defines as a valid substitute. The resulting UUID is still a standards-compliant v1.

Can I use v1 to recover when a record was created?

Yes — parse the timestamp fields out of the UUID and convert to Unix epoch. Some libraries (uuid-tools, Java UUID) expose this directly. Useful for forensics or debugging, but don't rely on it as a primary timestamp column — create a separate created_at field for that.