Cryptographically Secure
Uses Web Crypto API for generating truly random UUIDs with high entropy.
Developer Tool
UUID / GUID Generator
Generate universally unique identifiers instantly. Support for UUID v1, v4, v7, ULID, and Nano ID with bulk generation, validation, and multiple output formats.
Cryptographically Secure
Instant Generation
Bulk Support
550e8400
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e29b
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41d4
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a716
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446655440000
Click to generate...
UUID Version
Quantity
Output Format
Generated UUIDs (0)
Click "Generate UUIDs" to create unique identifiers
UUID Validator & Parser
Recent History
No recent generations
UUID Version Comparison
| Version | Size | Sortable | Time-Based | Randomness | Best For |
|---|---|---|---|---|---|
| UUID v1 | 128 bits | ✓ Partial | ✓ Yes | Low (MAC + clock) | Distributed systems |
| UUID v4 | 128 bits | ✗ No | ✗ No | High (122 bits) | General purpose |
| UUID v7 | 128 bits | ✓ Yes | ✓ Unix ms | Medium (74 bits) | Database primary keys |
| ULID | 128 bits | ✓ Yes | ✓ Unix ms | Medium (80 bits) | URL-safe, sortable IDs |
| Nano ID | Configurable | ✗ No | ✗ No | High | Short URL-friendly IDs |
Powerful UUID Generation Features
Bulk Generation
Generate up to 1000 UUIDs at once for batch processing and database seeding.
Multiple Versions
Support for UUID v1, v4, v7, ULID, and Nano ID to meet any requirement.
Validation & Parsing
Validate UUIDs and extract version, variant, and timestamp information.
Multiple Formats
Output in standard, uppercase, no hyphens, braces, or URN format.
Export Options
Copy to clipboard or download as text file for easy integration.
UUID Structure Explained
550e8400
time_low
32 bits
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e29b
time_mid
16 bits
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4
version
4 bits
1d4
time_hi
12 bits
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a
variant
2-3 bits
716
clock_seq
13-14 bits
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446655440000
node
48 bits
A UUID is 128 bits (16 bytes) represented as 32 hexadecimal digits, displayed in 5 groups separated by hyphens in the form 8-4-4-4-12.
Frequently Asked Questions
What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit identifier standardized by RFC 4122. UUIDs are designed to be unique across space and time without requiring a central registration authority. They are commonly used as:
- Database primary keys
- Session identifiers
- Transaction IDs
- File and resource identifiers
- API request tracking
What is the difference between UUID and GUID?
UUID and GUID are essentially the same thing:
- UUID (Universally Unique Identifier) - The standard term used in most contexts
- GUID (Globally Unique Identifier) - Microsoft's terminology for the same concept
Both are 128-bit identifiers represented as 32 hexadecimal characters with hyphens. The main difference is naming convention - GUID is commonly used in Microsoft/.NET ecosystems.
Which UUID version should I use?
- UUID v4 - Best for general purpose use. Completely random, simple to generate, and works well for most applications.
- UUID v1 - Use when you need time-ordering and have distributed systems where node ID helps prevent collisions.
- UUID v7 - Ideal for database primary keys. Provides time-ordering without exposing MAC addresses. Best for modern applications.
- ULID - When you need sortable, URL-safe identifiers with case-insensitivity.
- Nano ID - When you need shorter, URL-friendly IDs and can tolerate slightly higher collision risk.
What is UUID v7 and why is it recommended?
UUID v7 is a newer UUID format (RFC draft) that combines the best aspects of v1 and v4:
- Time-ordered: Uses Unix timestamp in milliseconds, making UUIDs naturally sortable
- Privacy-friendly: Doesn't expose MAC address like v1
- Database-optimized: Sequential ordering improves index performance
- Random component: Still includes random bits for uniqueness
UUID v7 is recommended for new projects, especially when used as database primary keys.
Are UUIDs truly unique?
While not mathematically guaranteed, the probability of collision is astronomically low:
- UUID v4 has 122 random bits, giving 5.3 × 10^36 possible values
- To have a 50% chance of collision, you'd need approximately 2.71 × 10^18 UUIDs
- Generating 1 billion UUIDs per second would take 85 years to reach 50% collision probability
For all practical purposes, UUID collisions are impossible in real-world applications.
What is a ULID?
ULID (Universally Unique Lexicographically Sortable Identifier) is an alternative to UUID with specific advantages:
- Sortable: Lexicographically sortable by timestamp
- URL-safe: Uses Crockford's Base32 encoding (no special characters)
- Case-insensitive: Can be compared case-insensitively
- Same size: 128 bits like UUID
- Format: 26 characters (vs 36 for UUID with hyphens)
What is Nano ID?
Nano ID is a tiny, secure, URL-friendly unique string ID generator:
- Shorter: Default 21 characters (configurable 8-36)
- URL-safe: Uses A-Za-z0-9_- alphabet
- Secure: Uses cryptographic randomness
- No dependencies: Lightweight implementation
- Similar collision probability: 21 chars ≈ UUID v4 collision risk
How are UUIDs used in databases?
UUIDs are commonly used as primary keys in databases:
- Distributed systems: Generate IDs without central coordination
- Security: Non-guessable IDs prevent enumeration attacks
- Merging data: Easy to merge databases without ID conflicts
- Sharding: Natural distribution across database shards
For optimal performance, use UUID v7 or ULID as they maintain insertion order and improve index efficiency.