What is the difference between UUID v4 and UUID v7?

UUID v4 is fully random. UUID v7 is timestamp-prefixed and sorts chronologically, which improves database index performance at scale. Both are globally unique.

Are the generated UUIDs truly unique?

For all practical purposes, yes. With 2¹²² possible v4 values, the probability of a collision is negligible even generating millions per second over decades.

Can I use these as database primary keys?

Absolutely — UUID primary keys are the standard in distributed systems. Use v4 for simplicity or v7 for better index performance in large tables.

Is this tool private?

All generation happens in your browser using crypto.randomUUID() . No identifiers are sent to our servers.

GUID Generator.

Generate cryptographically strong Globally Unique Identifiers with surgical precision for your applications and databases.

Technical Specifications

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What is a GUID?

A Globally Unique Identifier (GUID) is a 128-bit number used to identify information in computer systems. The total number of unique keys (2¹²⁸) makes the probability of the same number being generated twice virtually zero.

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Version 4 vs Version 7

Version 4 uses cryptographic randomness — the most common type for general use. Version 7 is time-ordered, enabling efficient database indexing while preserving uniqueness across distributed systems.

What Is a UUID / GUID Generator?

A UUID (Universally Unique Identifier) — also called a GUID (Globally Unique Identifier) — is a standardised 128-bit value defined in RFC 4122 that uniquely labels records, resources, and system components without any central authority. Our free UUID generator produces both UUID v4 (fully random) and UUID v7 (time-ordered) identifiers, with bulk generation of up to 20,000 at once and a range of output formats ready to copy or download.

Key Features

UUID v4: Cryptographically random using the Web Crypto API — the most common choice for general use
UUID v7: Timestamp-prefixed for monotonic sort order, improving database index efficiency at scale
Bulk generation: 1 to 20,000 UUIDs in a single batch
Output formats: Hyphenated, uppercase, curly-brace wrapped, double-quoted, or JSON array
Copy & download: One-click copy to clipboard or download as a .txt file
Zero friction: No account, no API key, no rate limits

How to Generate UUIDs Online

Choose your version — v4 for randomness, v7 for time-sortable keys
Set the quantity (1–20,000)
Select an output format (hyphenated, braces, uppercase, JSON, etc.)
Click Generate — results appear instantly
Copy to clipboard or download as a plain text file

Common Use Cases

Database primary keys: Replace auto-increment integers in distributed tables without coordination
API resource IDs: Give users, orders, and assets unpredictable, non-sequential identifiers
Session & correlation tokens: Unique per-request IDs for logging and distributed tracing
Test data fixtures: Populate test databases with non-conflicting, realistic IDs
File naming: Prevent conflicts and enumeration attacks on uploaded files

UUID v4 vs UUID v7 — Which Should You Use?

UUID v4 is entirely random and is the default choice for most applications. The trade-off is that random primary keys fragment database B-tree indexes over time, causing slower insert performance at scale. UUID v7 embeds a millisecond Unix timestamp in the first 48 bits. New UUIDs are always larger than previous ones, so inserts land at the end of the index — like auto-increment integers — while still being globally unique. Prefer v7 for any new project using PostgreSQL, MySQL 8+, or SQL Server.

Frequently Asked Questions

What is the difference between UUID v4 and UUID v7?: UUID v4 is fully random. UUID v7 is timestamp-prefixed and sorts chronologically, which improves database index performance at scale. Both are globally unique.
Are the generated UUIDs truly unique?: For all practical purposes, yes. With 2¹²² possible v4 values, the probability of a collision is negligible even generating millions per second over decades.
Can I use these as database primary keys?: Absolutely — UUID primary keys are the standard in distributed systems. Use v4 for simplicity or v7 for better index performance in large tables.
Is this tool private?: All generation happens in your browser using crypto.randomUUID(). No identifiers are sent to our servers.

Privacy & Security

All UUID generation runs client-side using the Web Crypto API. Nothing you generate is transmitted to our servers. There are no usage logs, no accounts, and no stored data.