Best UUID Generator

A UUID (Universally Unique Identifier) is a 128-bit number used to identify information across computer systems without a central authority. The standard format is 32 hex characters in five groups separated by hyphens — for example: 550e8400-e29b-41d4-a716-446655440000. UUID v4 alone has over 5.3 x 10^36 possible values. If you generated 1 billion UUIDs every second, it would take roughly 100 years to reach a 50% chance of a single duplicate. UUIDs are defined by RFC 9562 (which superseded RFC 4122 in 2024) and are natively supported in every major programming language and database.

There's no technical difference. GUID (Globally Unique Identifier) is what Microsoft calls it across .NET, SQL Server, and C#. UUID (Universally Unique Identifier) is the standard term from the RFC spec and everywhere else — Java, Python, PostgreSQL, Linux, and web standards. The format, length (128 bits), and generation algorithms are identical. This tool generates both — the output works as a UUID and a GUID.

This tool supports all major versions: v4 (random — recommended for most use cases), v7 (time-ordered — best for database primary keys), v5 (SHA-1 namespace — deterministic), v3 (MD5 namespace), v1 (timestamp + MAC address), v6 (reordered timestamp), NIL (all zeros), and MAX (all ones). UUID v4 is the most widely used and is generated using the Web Crypto API for cryptographic randomness.

UUID v4 (random) is the safe default — it works everywhere with no configuration. Use UUID v7 for database primary keys where insert order matters, because its timestamp prefix keeps B-tree indexes compact and avoids page splits. Use UUID v5 when you need the same input to always produce the same UUID. Use UUID v1 when you need the creation timestamp embedded in the ID.

Pick a UUID version from the dropdown (v4 is the default). Set how many UUIDs you need — from 1 to 1,000. UUIDs generate automatically when you change settings, or click Regenerate for a fresh batch. Copy to clipboard in plain text, JSON array, CSV, or JavaScript array format. Or download as TXT, CSV, JSON, or XML files. Everything runs in your browser — no server, no signup.

Yes. This UUID generator is completely free — no signup, no account, no usage limits. You can generate single or bulk UUIDs as often as you want.

In theory, yes. In practice, no. UUID v4 has 2^122 possible values — over 5.3 undecillion combinations. You'd need to generate 1 billion UUIDs per second for about 100 years to reach a 50% chance of a single collision. For all practical purposes, UUID collisions don't happen.

Yes. You can generate up to 1,000 UUIDs at once. Export them as plain text, JSON array, CSV, or XML — or download them as a file. Bulk generation is useful for database seeding, test data, and migration scripts.

Database primary keys (UUID v7 preserves insert order for better index performance), distributed systems (generate unique IDs across servers without coordination), web sessions and CSRF tokens (UUIDs prevent enumeration attacks), API request trace IDs and idempotency keys, test and seed data generation, and logging and audit trails (UUID v7 adds natural time-ordering for easier log analysis).

Yes. All UUIDs follow RFC 4122 and the newer RFC 9562 standard. Version 4 UUIDs use crypto.getRandomValues() from the Web Crypto API, which provides cryptographically secure randomness — the same source used by password managers and security tools.

Yes. UUIDs are commonly used as primary keys in PostgreSQL, MySQL, MongoDB, and DynamoDB. UUID v7 is the best choice for primary keys because its timestamp prefix preserves insert order and reduces index fragmentation. UUID v4 works well in distributed systems where ordering doesn't matter.

Yes. All UUIDs are generated entirely on your device using client-side JavaScript. No data gets sent to any server. The Web Crypto API makes sure the random numbers are cryptographically secure.

JavaScript (browsers and Node.js 19+): crypto.randomUUID() returns a UUID v4 string. For other versions, use the uuid npm package. Python: import uuid; uuid.uuid4() generates a random UUID. Java: UUID.randomUUID() from java.util.UUID. Go: use the google/uuid package. PostgreSQL: gen_random_uuid() generates UUID v4 natively. All produce RFC-compliant UUIDs safe for production use.

UUID v7 was introduced in RFC 9562. It starts with a Unix timestamp in milliseconds, followed by random bits. UUIDs generated later always sort after earlier ones. For databases, this preserves insert order, keeps B-tree indexes compact, and avoids the page splits that random UUID v4 values cause. If you're picking a UUID version for a new database schema, v7 is the best option.