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UUID Generator

Generate UUID v4 identifiers one at a time or in bulk. Use them for database records, API resources, test fixtures, request IDs, distributed systems, and collision-resistant object identifiers.

Last updated: March 25, 2026

Client-Side Processing
Input Data Stays on Device
Instant Local Execution
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What is UUID Generator?

A UUID (Universally Unique Identifier) is a 128-bit identifier standardized by RFC 4122. Formatted as 32 hexadecimal characters split into 5 groups (e.g. 550e8400-e29b-41d4-a716-446655440000), UUIDs are designed to be globally unique across all computers and all time — no central authority is needed to coordinate them. This makes them ideal for distributed databases, microservices, and any system where multiple nodes must independently create unique identifiers.

UUID v4 — which this tool generates — uses cryptographically secure random numbers for all 122 of its variable bits (6 bits are fixed for version and variant). The probability of generating the same UUID twice is so astronomically small that it is considered practically impossible: you could generate one billion UUIDs per second for 85 years and have only a 50% chance of one collision.

How to Use UUID Generator

1

Choose how many UUIDs to generate using the quantity dropdown (1 to 100)

2

Select your preferred format — lowercase (default), UPPERCASE, or without hyphens

3

Click "Generate" to create a fresh batch of UUIDs

4

Click the copy icon next to any UUID to copy it individually

5

Click "Copy All" to copy the entire list, one UUID per line, for bulk use

Common Use Cases

  • Primary keys for PostgreSQL, MySQL, or MongoDB database records
  • Unique identifiers for REST API resources (e.g. /users/{uuid})
  • Request correlation IDs for distributed tracing and logging (Datadog, Jaeger)
  • Idempotency keys for payment APIs (Stripe, PayPal) to prevent duplicate charges
  • Session tokens and state parameters for OAuth 2.0 flows
  • File and asset naming to avoid collisions in S3 or cloud storage
  • Event tracking IDs for analytics pipelines
  • Testing: populating fixtures and seed data with unique IDs

Example Input and Output

A UUID v4 always follows the 8-4-4-4-12 format. The version character (4) and variant bits are the only fixed portions — everything else is random.

UUID Format: 8-4-4-4-12 hex groups
xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx
(where x = random hex, 4 = version, y = variant bits 8, 9, a, or b)
Sample UUID v4 output
f47ac10b-58cc-4372-a567-0e02b2c3d479
3d5c2a9e-7f1b-4d8a-b3e6-1a2c4f8e9d0b
a1b2c3d4-e5f6-4789-8012-abcdef012345

How This Tool Works

The tool calls the browser's crypto.randomUUID() method, which implements RFC 4122 UUID v4 generation using the operating system's cryptographically secure random source. On older browsers, it falls back to crypto.getRandomValues() filling a 16-byte Uint8Array, then manually sets version bits (bits 12-15 to 0100) and variant bits (bits 6-7 to 10) before formatting as hex strings with hyphens.

Technical Stack

crypto.randomUUID() (Web Crypto API)Client-side onlyRFC 4122 compliantNo external libraries

Privacy Guarantee

UUID generation uses only browser-native cryptographic APIs. No generated IDs are sent to or logged by our servers — they exist only in your browser and clipboard.

Database Indexing Tip

If using UUIDs as primary keys in PostgreSQL, consider storing them as UUID type (not VARCHAR) and using the pg_trgm extension or a BRIN index if query performance on ID columns becomes a concern.

Browser Compatibility

crypto.randomUUID() is available in all modern browsers (Chrome 92+, Firefox 95+, Safari 15.4+). This tool uses it natively — no polyfill or external library required.

Frequently Asked Questions

Are these UUIDs truly unique?

UUID v4 uses 122 random bits, giving 2¹²² possible values (approximately 5.3 × 10³⁶). The probability of any two UUIDs ever matching is negligible. At 1 billion per second across all computers on Earth for a trillion years, you would still be unlikely to see a collision.

What's the difference between UUID and GUID?

They are the same format. GUID (Globally Unique Identifier) is Microsoft's terminology for UUID. Both implement RFC 4122 and the identifiers are interchangeable. The different names simply reflect different ecosystem origins (IETF vs. Microsoft COM).

What UUID version should I use?

Use UUID v4 (random) for general-purpose IDs — it is the simplest and most widely supported. UUID v7 (time-ordered random, 2022 RFC draft) is gaining traction for database primary keys where sortability matters. UUID v1 (MAC address + timestamp) leaks network identity and is now discouraged.

Can I use UUIDs as database primary keys?

Yes, and it is common in distributed systems. The trade-off: UUID v4 is random so it causes index fragmentation in B-tree indexes (PostgreSQL, MySQL). Solutions include using UUID v7 (time-ordered), storing as a bytea/binary type, or using ULID format. For small-to-medium databases, the practical impact is negligible.

Are UUIDs generated here cryptographically secure?

Yes. The tool uses crypto.randomUUID() (or crypto.getRandomValues() as fallback) — the browser's cryptographically secure pseudo-random number generator (CSPRNG). The entropy comes from OS-level sources (hardware, interrupt timing) that are suitable for security-sensitive applications.

What is the difference between UUID v4 and ULID?

ULID (Universally Unique Lexicographically Sortable Identifier) encodes a millisecond-precision timestamp in its first 10 characters, making it sortable by creation time. UUID v4 is fully random with no time component. Use ULID if natural sort order matters (e.g. feed items, events). Use UUID v4 for simplicity and RFC compliance.

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