UUID Generator

What is UUID Generator?

UUID Generator is a free online tool for generating UUIDs (Universally Unique Identifiers). Also known as GUIDs (Globally Unique Identifiers), UUIDs are 128-bit numbers used to uniquely identify information in computer systems without requiring a central authority.

This tool supports multiple UUID versions (v1, v4, v5) and allows you to customize the format with options for uppercase conversion and dash removal. Whether you need a single UUID or bulk generation of thousands, this tool makes it quick and easy.

What is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit label used for information identification. When generated according to standard methods, UUIDs are for practical purposes unique, without requiring a central registration authority.

Standard UUID Format

A UUID is typically displayed as 32 hexadecimal digits separated by hyphens:

123e4567-e89b-12d3-a456-426614174000

Format: xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx

Where:

• x is any hexadecimal digit (0-9, a-f)
• M indicates the UUID version (1, 4, 5, etc.)
• N indicates the UUID variant

How to use UUID Generator?

Quick Generate

The fastest way to generate a UUID:

1. Click one of the Quick Generate buttons:

   • UUID v1 - Timestamp-based UUID
   • UUID v4 - Random UUID (most common)
   • NIL UUID - Special all-zeros UUID

2. The UUID appears instantly in the output area.

3. Click Copy to copy to clipboard.

Custom Generation

For more control over UUID generation:

1. Select UUID Version from dropdown:

   • Version 1: Timestamp-based with MAC address
   • Version 4: Randomly generated (recommended)
   • Version 5: Name-based using SHA-1 hash
   • NIL UUID: All zeros (00000000-0000-0000-0000-000000000000)

2. Set Quantity (1-1000) for bulk generation.

3. For UUID v5, provide:

   • Namespace UUID: The namespace identifier
   • Name: The name to hash

4. Choose formatting options:

   • Uppercase: Convert to uppercase letters
   • Remove dashes: Remove hyphens from UUID

5. Click Generate UUIDs button.

6. Use Copy to copy all generated UUIDs.

Features

• Multiple UUID versions - v1, v4, v5, and NIL UUID support
• Quick generation - One-click generation for common use cases
• Bulk generation - Generate up to 1000 UUIDs at once
• Custom formatting - Uppercase and dash removal options
• UUID v5 support - Name-based generation with custom namespace
• Error handling - Clear validation and error messages
• Instant copy - Easy clipboard copy functionality
• Browser-based - No server required, completely private

UUID Versions Explained

UUID Version 1 (Timestamp-based)

Generated from: Current timestamp + MAC address + random component

Format: xxxxxxxx-xxxx-1xxx-xxxx-xxxxxxxxxxxx

Example:

6c84fb90-12c4-11e1-840d-7b25c5ee775a

Use cases:

• When temporal ordering is important
• Database primary keys with chronological sorting
• Distributed systems requiring time-based coordination

Characteristics:

• Predictable sequence over time
• Can reveal MAC address and timestamp
• Guaranteed unique across space and time

UUID Version 4 (Random)

Generated from: Random or pseudo-random numbers

Format: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx

Example:

550e8400-e29b-41d4-a716-446655440000

Use cases:

• General-purpose unique identifiers
• Session IDs
• Transaction IDs
• Object identifiers
• Most common choice for new projects

Characteristics:

• Completely random
• No information leakage
• Extremely low collision probability (1 in 2^122)

UUID Version 5 (Name-based SHA-1)

Generated from: SHA-1 hash of namespace + name

Format: xxxxxxxx-xxxx-5xxx-yxxx-xxxxxxxxxxxx

Example:

886313e1-3b8a-5372-9b90-0c9aee199e5d

Use cases:

• Deterministic UUID generation
• Same input always produces same UUID
• URL namespaces
• DNS namespaces
• Content-addressed storage

Characteristics:

• Reproducible
• Name-based generation
• Namespace isolation
• Collision-resistant

NIL UUID

Value: All zeros

Format: 00000000-0000-0000-0000-000000000000

Use cases:

• Default/placeholder value
• Null object pattern
• Initialization value

Common Use Cases

1. Database Primary Keys

Use UUIDs as primary keys for distributed databases:

CREATE TABLE users (
  id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
  username VARCHAR(50),
  email VARCHAR(100)
);

Benefits:

• No central ID generator needed
• Merge databases without conflicts
• Globally unique across all systems

2. API Request IDs

Track API requests with unique identifiers:

const requestId = '550e8400-e29b-41d4-a716-446655440000';
logger.info(`Request ${requestId} started`);

3. File Names

Generate unique file names:

document-6c84fb90-12c4-11e1-840d-7b25c5ee775a.pdf
image-550e8400-e29b-41d4-a716-446655440000.jpg

4. Session Management

Create unique session identifiers:

const sessionId = generateUUID();
sessionStorage.setItem('sessionId', sessionId);

5. Microservices Communication

Trace requests across microservices:

X-Request-ID: 6c84fb90-12c4-11e1-840d-7b25c5ee775a
X-Correlation-ID: 550e8400-e29b-41d4-a716-446655440000

6. Distributed Systems

Coordinate across distributed systems without conflicts:

const nodeId = '6c84fb90-12c4-11e1-840d-7b25c5ee775a';
const eventId = '550e8400-e29b-41d4-a716-446655440000';

Formatting Options

Standard Format

550e8400-e29b-41d4-a716-446655440000

Uppercase

550E8400-E29B-41D4-A716-446655440000

Without Dashes

550e8400e29b41d4a716446655440000

Uppercase Without Dashes

550E8400E29B41D4A716446655440000

UUID Best Practices

Choosing the Right Version

Use UUID v4 when:

• You need maximum randomness
• Privacy is important
• You don't need reproducibility
• General-purpose identifiers

Use UUID v1 when:

• Temporal ordering matters
• You need chronological sorting
• Working with legacy systems
• Time-based coordination needed

Use UUID v5 when:

• You need deterministic generation
• Same input should produce same UUID
• Content-addressed systems
• URL/DNS namespaces

Storage Considerations

Binary vs String Storage:

Binary (16 bytes):

BINARY(16) -- MySQL
UUID -- PostgreSQL

String (36 bytes with dashes):

CHAR(36) -- MySQL
VARCHAR(36) -- PostgreSQL

Recommendation: Use native UUID type or binary storage for efficiency.

Performance Tips

1. Indexing: UUIDs as primary keys may cause index fragmentation. Consider:

   • Using UUID v1 for better sequential ordering
   • Adding separate sequential ID for ordering
   • Using time-based prefixes

2. Storage: Store UUIDs in binary format to save space and improve performance

3. Generation: Generate UUIDs client-side to reduce server load

Security Considerations

UUID v1 Concerns:

• Exposes MAC address
• Reveals generation timestamp
• Predictable sequence

UUID v4 Security:

• Use cryptographically secure random number generator
• Suitable for security tokens
• No information leakage

UUID v5 Security:

• Deterministic but secure
• SHA-1 hash provides collision resistance
• Namespace isolation

Frequently Asked Questions

Q: Are UUIDs truly unique?

A: While not mathematically guaranteed, the probability of collision is so low (approximately 1 in 2^122 for UUID v4) that they are considered unique for practical purposes. You'd need to generate billions of UUIDs per second for thousands of years to have a 50% chance of collision.

Q: Which UUID version should I use?

A: For most applications, UUID v4 (random) is recommended. It's simple, secure, and has no information leakage. Use v1 if you need chronological ordering, or v5 if you need deterministic generation.

Q: Can I use UUIDs as database primary keys?

A: Yes, but be aware of potential index fragmentation issues. UUID v1 provides better sequential ordering for database indexes. Consider your database system's native UUID support and indexing strategies.

Q: How do I generate UUIDs in my code?

A: Most programming languages have UUID libraries:

• JavaScript: crypto.randomUUID() or uuid package
• Python: uuid module
• Java: java.util.UUID
• C#: System.Guid.NewGuid()
• PHP: Ramsey\Uuid

Q: Are UUIDs case-sensitive?

A: No, UUIDs are case-insensitive. 550e8400-e29b-41d4-a716-446655440000 and 550E8400-E29B-41D4-A716-446655440000 represent the same UUID.

Q: Can I remove the dashes from UUIDs?

A: Yes, the dashes are just formatting. The UUID without dashes is equally valid and often used for shorter representations or URL-safe identifiers.

Q: What is the NIL UUID?

A: The NIL UUID (all zeros: 00000000-0000-0000-0000-000000000000) is a special UUID used to represent null or empty values in UUID-based systems.

UUID Standards

UUIDs are defined by:

• RFC 4122: A Universally Unique IDentifier (UUID) URN Namespace
• ISO/IEC 9834-8: Information technology standards

Privacy & Security

Your privacy is important to us:

• No data is sent to any server
• All UUID generation happens in your browser
• No cookies or tracking
• No account or login required
• Completely free to use

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