Can two UUID v4 values ever collide?

The probability of a collision in UUID v4 is practically zero — about 1 in 2.71 quintillion, which would require generating billions of UUIDs per second for decades.

Should I use UUID v4 or v7?

Use v7 when IDs double as database keys: its time-ordered prefix keeps B-tree indexes dense. Use v4 when unpredictable randomness matters more than ordering.

Is UUID v1 still appropriate?

v1 embeds the MAC address and timestamp, which leaks hardware identity and is not privacy-friendly. It is provided for legacy compatibility — prefer v4 or v7 for new systems.

UUID / GUID Generator — v1

Tool Guide

UUID / GUID Generator — v1, v4 & v7: What It Does

Generates RFC 9562 UUIDs in bulk using cryptographic randomness. It supports random v4 identifiers, timestamp-ordered v7 keys, timestamp-based v1 legacy IDs, and nil UUIDs, with embedded timestamp inspection for database debugging.

Example

Input

v4, count 1

Output

550e8400-e29b-41d4-a716-446655440000 (format sample; actual IDs vary)

Emits a 128-bit hyphenated hexadecimal identifier drawn from cryptographic randomness.

How to Use

Select UUID version: v4 (random), v7 (time-ordered), v1 (legacy timestamp), or nil.
Specify the desired batch quantity (1 to 1,000) and formatting.
Copy the generated identifiers as plain text, JSON array, or SQL values.

Limitations

UUIDs generated with crypto.getRandomValues cannot be reproduced once cleared.
Browser clipboard limits cap bulk exports to 10,000 items per batch.

Frequently Asked Questions

Why is UUID v7 preferred over UUID v4 for database primary keys?

UUID v7 embeds a 48-bit Unix timestamp prefix, keeping B-tree index insertions sequential and avoiding page splits common with random v4 keys.

What is the collision probability of UUID v4?

With 122 random bits, you would need to generate over 2.7 quintillion UUIDs before reaching a one-in-a-billion collision chance.

Command-Line Equivalent

python3 -c 'import uuid; print(uuid.uuid4())'

Generate a v4 UUID with Python.

Embed or Cite UUID / GUID Generator — v1, v4 & v7

Embed this interactive utility directly into documentation or blog posts, or link via GitHub badge:

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HTML Embed Code (iframe):

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