UUID Generator

Generate Unique Identifiers Instantly

Free online UUID/GUID generator for creating RFC 4122 compliant universally unique identifiers. Generate single or multiple UUIDs (v4) with cryptographically secure randomness. Perfect for database primary keys, API request tracking, session management, and distributed systems. All generation happens in your browser - no data is sent to our servers.

How to Use UUID Generator

Generating UUIDs is simple and instant:

Step 1: Select Quantity

Choose how many UUIDs you need (1-100). For single UUID generation, leave at default.

Step 2: Generate UUIDs

Click the 'Generate UUIDs' button. Multiple cryptographically secure UUIDs will be created instantly using your browser's Web Crypto API.

Step 3: Copy and Use

Copy individual UUIDs by clicking the copy button next to each, or use 'Copy All' to copy the entire list. Paste directly into your code, database, or configuration files.

All UUIDs are generated locally in your browser using cryptographically secure randomness (window.crypto.getRandomValues()). No data is transmitted to our servers, ensuring complete privacy and security.

UUID Generator

Number of UUIDs

Generate 1 to 100 UUIDs at once

Practical Use Cases for UUID Generator

UUIDs (Universally Unique Identifiers) are essential in modern software development:

Database Primary Keys

Use UUIDs as primary keys in distributed databases (PostgreSQL, MongoDB, Cassandra) to eliminate ID collisions across multiple servers, data centers, or partitions. Unlike auto-increment IDs, UUIDs can be generated offline and merged without conflicts.

API Request & Transaction IDs

Generate unique identifiers for API requests, HTTP transactions, and distributed tracing (OpenTelemetry, Zipkin). UUIDs enable end-to-end request tracking across microservices and help debug distributed systems.

File & Resource Naming

Create collision-free filenames for user uploads, temporary files, cache keys, and cloud storage objects (AWS S3, Azure Blob). UUIDs prevent filename conflicts in multi-user environments.

Session & Token Management

Generate secure session IDs, authentication tokens, CSRF tokens, and API keys. UUIDs provide high entropy making them resistant to guessing attacks (when combined with proper security practices).

Event & Message IDs

Assign unique identifiers to events in event-driven architectures, message queues (RabbitMQ, Kafka), and pub/sub systems. UUIDs enable message deduplication and idempotent processing.

Entity & Object Identifiers

Identify entities in domain-driven design, aggregate roots, and business objects. UUIDs allow client-side ID generation before database persistence.

Correlation IDs for Logging

Track related log entries across distributed services using correlation IDs. UUIDs help trace user actions and debug issues in microservices architectures.

What is a UUID? Understanding Universally Unique Identifiers

A UUID (Universally Unique Identifier), also known as GUID (Globally 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.

UUID Format

UUIDs are typically represented as 32 hexadecimal digits displayed in five groups separated by hyphens: xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx (36 characters total including hyphens). Example: 550e8400-e29b-41d4-a716-446655440000

Structure Breakdown

Time Low (8 hex digits): Bits 0-31 of the timestamp
Time Mid (4 hex digits): Bits 32-47 of the timestamp
Time Hi and Version (4 hex digits): Bits 48-59 of timestamp + 4-bit version
Clock Sequence (4 hex digits): Helps avoid duplicates
Node (12 hex digits): Spatial uniqueness component

Uniqueness Probability

The probability of generating duplicate UUIDs is astronomically low. For UUID v4, generating 1 billion UUIDs per second would take approximately 85 years before reaching a 50% probability of a single collision.

UUID Versions Explained

RFC 4122 defines several UUID versions with different generation methods:

UUID v1 (Time-based)

Generated using current timestamp (60-bit) and MAC address. Predictable and reveals generation time and location. Not recommended for security-sensitive applications.

Use when: You need chronological sorting or want to embed timestamp information.

UUID v4 (Random) - Recommended

Generated using cryptographically strong pseudo-random numbers. 122 bits of randomness. Most widely used version due to simplicity and security. This tool generates v4 UUIDs.

Use when: You need unpredictable, globally unique identifiers for general purposes. Best choice for most applications.

UUID v5 (SHA-1 Hash-based)

Like v3 but uses SHA-1 instead of MD5. Deterministic and more secure than v3. Useful for generating consistent UUIDs from names.

Use when: You need deterministic UUIDs derived from names with better security than v3.

Benefits of Using UUIDs

Decentralized Generation

UUIDs can be generated independently on any system without coordination, central authority, or database access. Perfect for offline-first applications, distributed systems, and microservices.

Horizontal Scalability

Unlike sequential IDs, UUIDs don't require database round-trips or locks for generation. Multiple servers can generate IDs simultaneously without conflicts, enabling linear scalability.

Non-Sequential & Unpredictable

UUID v4 values are random and unpredictable, preventing enumeration attacks. Unlike auto-increment IDs (1, 2, 3...), attackers cannot guess or iterate through UUIDs to access resources.

No Information Leakage (v4)

Unlike UUID v1, version 4 UUIDs don't contain timestamps, MAC addresses, or other identifying information. Prevents information disclosure vulnerabilities.

Best Practices for UUID Usage

Choose the Right Version

Use UUID v4 for most applications. Use v5 only when you need deterministic generation from names. Avoid v1 unless you specifically need timestamp-based ordering.

Efficient Storage

Store UUIDs as 16-byte binary data instead of 36-character strings to save 55% space. Most databases support native UUID types (PostgreSQL: uuid, MySQL: BINARY(16)).

Validate UUID Format

Always validate UUID format on input using regex: ^[0-9a-f]{8}-[0-9a-f]{4}-[1-5][0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$ (case-insensitive).

Lowercase Convention

Always use lowercase letters in UUID strings for consistency (recommended by RFC 4122). Most systems are case-insensitive but standardizing on lowercase prevents issues.

Frequently Asked Questions (FAQ)

What's the difference between UUID and GUID?

UUID (Universally Unique Identifier) and GUID (Globally Unique Identifier) refer to the same concept. GUID is the Microsoft term, while UUID is the standardized term in RFC 4122. They are interchangeable.

Can two UUIDs ever be the same?

While theoretically possible, the probability is so low it's effectively impossible. For UUID v4, you would need to generate billions of UUIDs per second for decades to have even a 50% chance of a single collision.

Are UUIDs secure for authentication tokens?

UUID v4 provides good randomness but shouldn't be the only security measure. For authentication tokens, combine UUIDs with expiration times, HMAC signatures, or use dedicated token formats like JWT with proper signing.

How do I store UUIDs in databases efficiently?

Store as native UUID type (PostgreSQL) or BINARY(16) (MySQL) instead of VARCHAR(36). This saves 55% storage space and improves index performance. Convert string representation to binary using database functions.

Can I use UUIDs as database primary keys?

Yes, but be aware of performance implications. Random UUIDs (v4) can cause B-tree index fragmentation. For better performance, consider UUID v7, ULID, or use auto-increment IDs with UUID as an alternate key.

Do UUIDs work across different programming languages?

Yes, UUIDs are language-agnostic. The RFC 4122 standard ensures all implementations generate compatible UUIDs. Most languages have built-in UUID libraries (Python: uuid, Java: java.util.UUID, JavaScript: crypto.randomUUID()).

Should I include hyphens in UUIDs?

Standard representation includes hyphens (8-4-4-4-12), but some systems store them without hyphens to save space. Both are valid - choose based on your system's conventions. Be consistent within your application.

Is this tool free to use?

Yes, completely free with no registration required. Generate unlimited UUIDs instantly. All processing happens in your browser - no data is stored on our servers.