GUID/UUID Generator
Generate unique identifiers instantly with support for UUID v1, v4, v5, and GUID formats. Perfect for databases, APIs, and distributed systems.
Key Features
- UUID v4 Generation – Random UUIDs for maximum uniqueness
- UUID v1 Support – Time-based UUIDs with timestamps
- UUID v5 Generation – Name-based UUIDs with SHA-1
- GUID Format – Microsoft GUID compatibility
- Bulk Generation – Generate multiple UUIDs at once
- Format Options – Uppercase, lowercase, braces, hyphens
- Copy to Clipboard – One-click copying
- UUID Validation – Verify UUID format and version
- Browser-Based – No server calls, instant generation
- No Data Storage – All processing done locally
UUID/GUID Formats
UUID v4 (Random)
Method: Cryptographically secure random generation
Uniqueness: 122 random bits (extremely high)
Collision Risk: Effectively zero
Best for: General-purpose unique identifiers, database primary keys, session IDs
Example:f47ac10b-58cc-4372-a567-0e02b2c3d479
UUID v1 (Time-based)
Method: Timestamp + MAC address + clock sequence
Uniqueness: Time-ordered, traceable to machine
Collision Risk: Very low with proper implementation
Best for: Distributed systems needing time ordering, audit logs, event tracking
Example:6ba7b810-9dad-11d1-80b4-00c04fd430c8
UUID v5 (Name-based)
Method: SHA-1 hash of namespace + name
Uniqueness: Deterministic based on input
Collision Risk: Same input = same UUID
Best for: Reproducible IDs from URLs, DNS names, content-based addressing
Example:886313e1-3b8a-5372-9b90-0c9aee199e5d
Common Use Cases
🗄️ Database Primary Keys
- Globally unique – No coordination needed across systems
- Distributed databases – Perfect for sharded/replicated data
- Merge-friendly – No ID conflicts when combining databases
- Security – Non-sequential IDs prevent enumeration attacks
🔌 API Development
- Request IDs – Track requests across microservices
- Session tokens – Unique session identifiers
- Resource identifiers – REST API resource URLs
- Correlation IDs – Distributed tracing and logging
☁️ Cloud Applications
- File names – Unique storage keys (S3, Azure Blob)
- Transaction IDs – Payment and order tracking
- Message queues – Message deduplication
- Cache keys – Distributed caching systems
🖥️ Software Development
- Component IDs – React/Vue component keys
- Test data – Generate unique test fixtures
- COM objects – Windows GUIDs for COM registration
- Build artifacts – Version identification
UUID Best Practices
✅ Best Practices
- Use UUID v4 for general-purpose identifiers
- Store as binary (128 bits) for database efficiency
- Index properly – Use B-tree indexes for lookups
- Generate server-side for security-critical systems
- Validate format before using in queries
- Use lowercase for consistency and case-sensitive systems
❌ Avoid These
- Don’t use UUID v1 if MAC address privacy is a concern
- Don’t rely on sorting – UUIDs aren’t sequential
- Don’t generate client-side for sensitive operations
- Avoid string storage – wastes 36 bytes vs 16 bytes binary
- Don’t use as display IDs – too long for users
- Don’t assume uniqueness without proper RNG
Frequently Asked Questions
What’s the difference between UUID and GUID?
Technically, they’re the same. GUID (Globally Unique Identifier) is Microsoft’s term for UUID (Universally Unique Identifier). The format and generation methods are identical. GUIDs are often displayed with uppercase letters and braces {XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}, while UUIDs typically use lowercase without braces.
Are UUIDs truly unique?
Practically, yes. UUID v4 has 122 random bits, giving 5.3×10³⁶ possible values. The probability of collision is so astronomically low that it’s considered negligible for all practical purposes. You’d need to generate billions of UUIDs per second for thousands of years to have even a tiny chance of collision.
Which UUID version should I use?
For most cases, use UUID v4. It’s random, secure, and requires no configuration. Use UUID v1 if you need time-ordered IDs or want to preserve timestamp information. Use UUID v5 if you need reproducible IDs from the same input (e.g., generating the same UUID from a URL every time).
Can I use UUIDs as database primary keys?
Yes, but with considerations. UUIDs make excellent primary keys for distributed systems and prevent enumeration attacks. However, they’re larger than integers (16 vs 4-8 bytes) and random ordering can hurt database performance. Store as binary (not string), use proper indexing, and consider ULID or UUID v7 for better performance in high-write scenarios.
Is it safe to generate UUIDs in the browser?
Yes, for most purposes. Modern browsers use crypto.getRandomValues() for cryptographically secure random number generation. This is safe for session IDs, client-side identifiers, and non-security-critical operations. For highly sensitive systems (financial transactions, access tokens), generate UUIDs server-side where you have more control over the entropy source.
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