UUID Generator & Decoder

v4: Cryptographically random — best for most use cases

Click Generate to create a UUID

Format

Case

Quantity

UUID Decoder & Parser

Paste any UUID to instantly decode its version, variant, timestamp, and structure.

🔔 Stay Sharp

Get UUID tips, RFC updates, and dev tool news. No spam — just useful stuff.

✓ 2,400+ developers • Weekly • Unsubscribe anytime

What is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify information in computer systems. Unlike sequential IDs, UUIDs can be generated independently without coordination, making them perfect for distributed systems, databases, and APIs.

UUIDs are standardized by RFC 9562 (formerly RFC 4122) and are represented as 32 hexadecimal digits in 5 groups separated by hyphens:

xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx

Where M indicates the UUID version and N indicates the variant.

UUID Versions Explained

UUID v4 (Random)

Generated using random numbers with 2^122 possible combinations — the chance of collision is effectively zero for any practical application.

Best for: Most applications, databases, APIs, session tokens
Uniqueness: 2^122 possible values

UUID v1 (Timestamp-based)

Combines a timestamp, clock sequence, and node ID. Useful when you need to know when a UUID was created.

Best for: Ordered IDs, audit trails
Note: Contains timestamp information

UUID v3 (Name-based, MD5)

Generated by hashing a namespace + name using MD5. Deterministic — same inputs always produce the same UUID. Prefer v5 for new projects unless MD5 compatibility is required.

Best for: Legacy systems requiring MD5-based UUIDs, backward compatibility
Note: Uses MD5 (not cryptographically secure, but fine for UUID generation)

UUID v5 (Name-based, SHA-1)

Generated by hashing a namespace + name using SHA-1. Deterministic — same inputs always produce the same UUID.

Best for: Consistent IDs from names, deduplication, content addressing

UUID v6 (Reordered Timestamp)

UUID v6 is a reordered version of v1, rearranging the timestamp bits for natural sortability. It uses the same 60-bit Gregorian timestamp as v1 but places the most significant bits first.

Best for: Drop-in replacement for v1 when sortability matters
Advantage: Lexicographically sortable while retaining v1 compatibility

UUID v7 (Unix Epoch, Sortable)

The newest version from RFC 9562. Encodes a Unix timestamp in milliseconds, making v7 UUIDs naturally sortable by creation time.

Best for: Database primary keys, time-ordered events, distributed systems
Advantage: Sortable + random — better than v1 for modern databases

Common UUID Formats

Format	Example	Usage
Standard	`550e8400-e29b-41d4-a716-446655440000`	Most common
Braces	`{550e8400-e29b-41d4-a716-446655440000}`	Windows registry
URN	`urn:uuid:550e8400-e29b-41d4-a716-446655440000`	RFC 4122 URN
No hyphens	`550e8400e29b41d4a716446655440000`	Compact storage

📚 Latest Articles

View all →

UUID Versions Explained: V1 vs V4 vs V7

Understand the differences between UUID v1, v4, v5, and v7. Learn which UUID version to use for databases, APIs, and distributed systems.

GUID vs UUID: What's the Difference?

GUID and UUID are often used interchangeably, but there are subtle differences. Learn what sets them apart and when each term applies.

UUID as Database Primary Key: Best Practices

Should you use UUIDs as primary keys? Learn the trade-offs, performance implications, and best practices for UUIDs in PostgreSQL, MySQL, and more.

How to Generate UUIDs in JavaScript, Python, Java, and Go

Code examples for generating UUIDs in every major programming language. Copy-paste snippets for JavaScript, Python, Java, Go, and more.

UUID Alternatives: ULID, NanoID, CUID, and Short UUID Compared

Compare UUID alternatives like ULID, NanoID, CUID, and short UUIDs. Learn when to use each and their trade-offs for unique ID generation.

Frequently Asked Questions

What is a UUID?

UUID stands for Universally Unique Identifier. It's a 128-bit number used to identify information in computer systems. UUIDs are designed to be unique across both space and time, making them ideal for distributed systems.

What's the difference between UUID versions (v1, v3, v4, v5, v6, v7)?

UUID v4 is randomly generated (best for most use cases). UUID v1 uses a timestamp + node ID. UUID v3 and v5 are deterministic — they hash a namespace and name using MD5 (v3) or SHA-1 (v5). UUID v6 is a reordered v1 for sortability. UUID v7 embeds a Unix timestamp for natural sort order, ideal for database primary keys.

Are these UUIDs truly unique?

UUID v4 has approximately 2^122 possible values, making the chance of collision astronomically small. For practical purposes, you can treat them as unique. UUID v1 includes timestamp and node information, further reducing collision chances.

Is this tool free to use?

Yes, completely free. No signup required, no rate limits, no data stored. Generate as many UUIDs as you need.

Can I generate UUIDs in bulk?

Absolutely. You can generate up to 10,000 UUIDs at once. Use the quantity slider or enter a specific number, then export the results as CSV, JSON, or plain text.

When should I use UUID v3?

UUID v3 uses MD5 hashing and is deterministic like v5. Use it when you need backward compatibility with systems that already use v3. For new projects, prefer v5 (SHA-1) as it's more collision-resistant.

When should I use UUID v6?

UUID v6 is a reordered version of v1 that puts the timestamp bits in sort order. Use it as a drop-in replacement for v1 when you need lexicographic sortability. For greenfield projects, consider v7 instead.

Do you have a UUID API?

Yes! We offer a free REST API at createuuid.com/api. Generate any UUID version via simple GET requests with CORS support. No API key required. See the API documentation for details.

When should I use UUID v5?

Use UUID v5 when you need deterministic IDs — for example, generating a consistent UUID from a domain name, URL, or user email. The same namespace + name will always produce the same UUID, which is useful for deduplication and content addressing.

When should I use UUID v7?

Use UUID v7 when you need sortable unique identifiers, especially for database primary keys. Unlike v4, v7 UUIDs are time-ordered, which means they don't cause B-tree fragmentation and result in better insert performance. UUID v7 is the recommended replacement for v1 in modern systems.

How do I decode or parse a UUID?

Use our UUID Decoder & Parser below the generator. Paste any UUID and it will show the version, variant, structural breakdown with color-coded segments, and — for timestamp-based UUIDs (v1, v6, v7) — the exact date and time embedded in the UUID, plus the node ID and clock sequence.

Can I extract the timestamp from a UUID?

Yes, for UUID v1, v6, and v7. These versions embed a timestamp in their structure. Our decoder extracts and displays the date in both human-readable and ISO 8601 formats. UUID v4 is purely random and does not contain a timestamp.

How do I validate a UUID?

The UUID Decoder doubles as a validator. Paste any UUID and it will tell you whether it's valid, which version it is, and provide a full structural breakdown. It accepts standard format, braces format, and URN format.