UUID/GUID Generator

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What Is a GUID / UUID?

A GUID (Globally Unique Identifier) or UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify resources in distributed systems. The standard format is 32 hexadecimal digits displayed in five groups separated by hyphens: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. The probability of generating two identical UUIDs is astronomically low — you would need to generate one billion UUIDs per second for 86 years to have a 50% chance of a collision.

UUID Versions

Version	Generation Method	Use Case
v1	Timestamp + MAC address	Time-ordered, but exposes hardware info
v4	Random/pseudo-random	Most common — simple, no information leakage
v5	SHA-1 hash of namespace + name	Deterministic — same input always produces same UUID
v7	Unix timestamp + random (new standard)	Time-ordered and database-friendly, replacing v1

Common Use Cases

• Database Primary Keys: Use GUIDs instead of auto-increment integers when records are created across multiple servers or services.
• API Resource Identifiers: Expose GUIDs in URLs instead of sequential IDs to prevent enumeration attacks.
• Distributed Systems: Generate unique IDs without a central coordination service.
• File Naming: Avoid naming collisions when multiple processes write files to shared storage.
• Session Tokens: Use UUIDs as session or correlation identifiers in web applications.
• Message Queues: Assign unique IDs to messages for deduplication and tracking.

How to Use This Tool

1. Click Generate to create a new GUID/UUID.
2. Choose the format (standard, no hyphens, braces, etc.).
3. Generate multiple GUIDs at once for batch operations.
4. Click any GUID to copy it to your clipboard.

Why Use This Tool?

• Generate cryptographically random UUIDs instantly.
• Multiple format options for different platforms and languages.
• Runs entirely in your browser using the Web Crypto API.
• Perfect for database keys, correlation IDs, and unique identifiers.

Frequently Asked Questions

Are GUIDs truly unique?

For practical purposes, yes. A v4 UUID has 122 random bits, giving 5.3 × 10³⁶ possible values. The chance of collision is negligible for any real-world application.

GUID vs UUID — what is the difference?

They are the same thing. "GUID" is the term used by Microsoft, while "UUID" is the industry standard term defined in RFC 4122. The format and generation algorithms are identical.

Should I use GUIDs as database primary keys?

GUIDs work well for distributed systems but can impact database performance due to their randomness (causing index fragmentation). Consider sequential GUIDs (v7) or NEWSEQUENTIALID() in SQL Server if using GUIDs as clustered primary keys.