UUID Generator - Generate v4, v7, and ULID Online

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What are UUIDs?

UUID (Universally Unique Identifier) is a 128-bit identifier that's practically guaranteed to be unique across time and space. Perfect for database primary keys, session IDs, file names, and any scenario requiring unique identifiers.

UUID Format

550e8400-e29b-41d4-a716-446655440000
8-4-4-4-12 hexadecimal digits

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UUID Versions Compared

Version	Generation Method	Use Case	Sortability
UUID v4	Random/Pseudo-random	General purpose, high entropy	❌ Not sortable
UUID v7	Timestamp + Random	Database keys, distributed systems	✅ Time-sortable
ULID	Timestamp + Random	Modern alternative, web-friendly	✅ Time-sortable

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UUID v4 - Random UUIDs

Characteristics

• 🎲 Purely Random: 122 bits of entropy
• 🔒 Cryptographically Strong: Unpredictable generation
• 🌐 Platform Independent: Works anywhere
• ⚡ High Performance: Fast generation

Example

f47ac10b-58cc-4372-a567-0e02b2c3d479

Best For

✅ Session IDs and tokens
✅ File upload identifiers
✅ API request tracking
✅ General-purpose unique keys

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UUID v7 - Timestamp-Based UUIDs

Characteristics

• 📅 Time-Ordered: Contains Unix timestamp
• 🔢 Sortable: Natural chronological ordering
• 🎲 Unique: Random suffix ensures uniqueness
• 🗄️ DB-Friendly: Better for database performance

Structure

018e2f5a-7b12-7890-abcd-ef1234567890
│       │    │    │    └─ Random (62 bits)
│       │    │    └─ Version & Random  
│       │    └─ Random
│       └─ Random
└─ Unix Timestamp (48 bits)

Best For

✅ Database primary keys
✅ Event logging and tracing
✅ Distributed system coordination
✅ Time-series data

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ULID - Universally Unique Lexicographically Sortable Identifier

Characteristics

• 📝 Base32 Encoding: URL-safe, case-insensitive
• 📅 Timestamp-Based: Sortable by creation time
• 🔤 Human-Readable: Easier to read and type
• 📏 Compact: 26 characters vs 36 for UUID

Format

01F4Z1R2K3M4N5P6Q7R8S9T0
01F4Z1R2K3 = Timestamp (10 chars)
M4N5P6Q7R8S9T0 = Random (16 chars)

Advantages

✅ Shorter: 26 vs 36 characters
✅ Sortable: Chronological ordering
✅ URL-Safe: No special characters
✅ Case-Insensitive: Avoids confusion

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Choosing the Right Identifier

Use UUID v4 when:

• Security and unpredictability are paramount
• Order doesn't matter
• Maximum compatibility is needed
• You need RFC 4122 compliance

Use UUID v7 when:

• You need time-based sorting
• Database performance is important
• Working with distributed systems
• You want UUID standard compliance

Use ULID when:

• You prefer shorter, readable identifiers
• Time-sorting is important
• URLs or user-facing IDs are needed
• Case sensitivity could cause issues

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Generation Examples

Bulk Generation

// Generate 10 UUID v4s
f47ac10b-58cc-4372-a567-0e02b2c3d479
550e8400-e29b-41d4-a716-446655440000
6ba7b810-9dad-11d1-80b4-00c04fd430c8
...

Programming Examples

JavaScript

// UUID v4
const uuid = crypto.randomUUID();

// ULID  
const ulid = generateULID();

Python

import uuid
# UUID v4
new_uuid = uuid.uuid4()

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Features

🔢 Multiple Formats — UUID v4, UUID v7, and ULID generation
⚡ Bulk Generation — Generate hundreds at once
📋 One-Click Copy — Copy individual IDs or entire lists
🎯 Format Options — With/without hyphens, uppercase/lowercase
🔒 Client-Side — Generated in your browser, never sent to servers
📊 Statistics — See generation stats and uniqueness info

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Security & Performance

Collision Probability

• UUID v4: 1 in 2^122 (practically impossible)
• UUID v7: Similar to v4 for random portion
• ULID: 1 in 2^80 per millisecond

Performance Tips

🚀 Use UUID v7 for database primary keys (better indexing)
🎯 Use ULIDs for user-facing identifiers
⚡ Generate in batches for high-volume applications
🗄️ Consider clustered vs non-clustered indexing impact

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