UUID / GUID Generator
Generate universally unique identifiers instantly. Supports UUID v4 (random), v1-like (timestamp), and various output formats.
Generated UUID
e487352b-7877-4531-8f3e-058e7019a139Validate UUID
Output Formats
550e8400-e29b-41d4-a716-446655440000550E8400-E29B-41D4-A716-446655440000550e8400e29b41d4a716446655440000{550e8400-e29b-41d4-a716-446655440000}urn:uuid:550e8400-e29b-41d4-a716-446655440000VQ6EAOKbQdSnFkRmVUQAAA==About UUIDs
What is a UUID?
A Universally Unique Identifier (UUID) is a 128-bit identifier that is unique across all devices and time. Also known as GUID (Globally Unique Identifier) in Microsoft systems.
UUID Versions
- v1: v1: Based on timestamp and MAC address
- v4: v4: Randomly generated (most common)
- v5: v5: Name-based using SHA-1
- Nil: Nil: All zeros, represents "no UUID"
🎲 Collision Probability
UUID v4 has 2¹²² possible values. You'd need to generate 1 billion UUIDs per second for about 85 years to have a 50% chance of a single collision.
How UUID Generation Works
- Select UUID version (v4 for random, v1 for timestamp-based, or nil for all zeros)
- Choose output format (lowercase, uppercase, no dashes, braces, URN, or base64)
- Set quantity if generating multiple UUIDs (up to 1000)
- Click 'Generate UUID' to create cryptographically secure identifiers
- Use the validator to verify any UUID format and version
Common Use Cases
Database Primary Keys
Use UUID v4 as primary keys in distributed databases to avoid collisions across servers. Example: 550e8400-e29b-41d4-a716-446655440000
Session IDs
Generate unique session identifiers for web applications. UUID v4 ensures no two sessions collide even across multiple servers.
API Request IDs
Track API requests with unique identifiers. Format as URN for logging: urn:uuid:550e8400-e29b-41d4-a716-446655440000
File Upload Tokens
Create unique tokens for file uploads. Use no-dashes format for shorter URLs: 550e8400e29b41d4a716446655440000
Frequently Asked Questions
What's the difference between UUID v4 and v1?
UUID v4 is randomly generated and most common. UUID v1 is timestamp-based and includes MAC address information. For most use cases, v4 is recommended.
Can two UUIDs be the same?
The probability is astronomically low. UUID v4 has 2¹²² possible values. You'd need to generate 1 billion UUIDs per second for 85 years to have a 50% chance of a single collision.
What format should I use?
Standard lowercase format (550e8400-e29b-41d4-a716-446655440000) is most common. Use no-dashes for shorter URLs, braces for Microsoft systems, or URN for logging.
Is UUID the same as GUID?
Yes, GUID (Globally Unique Identifier) is Microsoft's term for UUID. They're functionally identical, though GUIDs are often displayed with braces: {550e8400-e29b-41d4-a716-446655440000}.
Can I use UUIDs in URLs?
Yes, but use URL-safe formats. Standard UUIDs with dashes work fine. For shorter URLs, use the no-dashes format. Avoid base64 format in URLs as it may contain special characters.
How do I validate a UUID?
Use the built-in validator in this tool. It checks format, version, and recognizes standard, no-dashes, and braces formats. Valid UUIDs follow the pattern: 8-4-4-4-12 hexadecimal characters.
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