UUID Generator
🆔 What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit value used to uniquely identify information in computer systems. First standardized by the Open Software Foundation (OSF) and later formalized in RFC 4122, UUIDs have become the de facto standard for generating unique identifiers without requiring a central authority or coordination between systems.
UUID v4 is generated using cryptographically secure random numbers, making collisions astronomically unlikely—you'd need to generate about 2.71 quintillion UUIDs before having a 50% chance of a collision. This makes UUID v4 ideal for most applications where guaranteed uniqueness is critical.
A typical UUID follows the 8-4-4-4-12 format:
⚙️ How This UUID Generator Works
This tool uses the Rust uuid crate compiled to WebAssembly, leveraging your browser's cryptographically secure random number generator (CSPRNG) to create truly random UUID v4 values. Everything runs locally in your browser—no server requests, no data collection.
🔥 Core Capabilities:
- Instant Generation:Create a new random UUID v4 with a single click—no page reload needed
- One-Click Copy:Click directly on the UUID to copy it to your clipboard instantly
- RFC 4122 Compliant:All generated UUIDs strictly follow the RFC 4122 version 4 specification
- Cryptographically Secure:Uses your browser's CSPRNG for maximum randomness and security
- 100% Local Processing:All generation happens in your browser—works offline too
- Zero Dependencies:No external APIs or services required
📊 UUID Structure Explained
xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx
- x:Random hexadecimal digit (0-9, a-f)
- M:Version number (4 for UUID v4)
- N:Variant indicator (8, 9, a, or b for RFC 4122)
The 32 hexadecimal characters represent 128 bits of data, with specific positions reserved for version and variant information.
📚 UUID Versions Overview
UUID v1 - Time-based
Generated from timestamp and MAC address. Reveals creation time and hardware info.
UUID v3 - Name-based (MD5)
Generated from namespace and name using MD5 hash. Same input always produces same UUID.
UUID v4 - Random ⭐ (This Tool)
Generated from cryptographically secure random numbers. Most widely used version.
UUID v5 - Name-based (SHA-1)
Similar to v3 but uses SHA-1 hash. Preferred over v3 for new applications.
UUID v7 - Time-ordered Random
New draft standard combining timestamp prefix with random data. Database-friendly.
💼 Practical Use Cases
1. 🗄️ Database Primary Keys
UUIDs are perfect for distributed databases where multiple servers need to generate unique IDs independently. Unlike auto-incrementing integers, UUIDs don't require coordination between database nodes and don't reveal record counts or creation order.
2. 🔐 API & Session Tokens
Generate unique tokens for API authentication, session management, password reset links, and email verification. The randomness of UUID v4 makes them impossible to guess, though they should still be combined with other security measures for sensitive operations.
3. 📁 File & Resource Naming
Avoid filename collisions when users upload files or when systems generate reports. UUID-based names ensure uniqueness across all uploads without checking for existing files.
4. 🌐 Distributed Systems
Microservices, message queues, and event-driven architectures rely on UUIDs for correlation IDs, transaction tracking, and ensuring message uniqueness across distributed components.
5. 📊 Analytics & Tracking
Assign unique identifiers to users, sessions, or events for analytics purposes. UUIDs work well for client-side ID generation where you can't rely on server coordination.
6. 🔗 URL Shorteners & Permalinks
Create unpredictable, unique identifiers for shortened URLs or permanent links. The randomness prevents enumeration attacks where malicious users try to guess valid URLs.
❓ Frequently Asked Questions
Q: Are UUIDs really unique?
A: Practically speaking, yes. A UUID v4 has 122 random bits, giving approximately 5.3 × 10³⁶ possible values. The probability of generating duplicate UUIDs is so low that you'd need to generate 1 billion UUIDs per second for about 85 years to have a 50% chance of a single collision.
Q: What standard does this tool follow?
A: All UUIDs generated strictly conform to RFC 4122 version 4 specification. The version digit is always '4' and the variant bits are set correctly (8, 9, a, or b in the first position after the third hyphen).
Q: Can I use this tool offline?
A: Absolutely! Once the page loads, all UUID generation happens locally in your browser using WebAssembly. No internet connection is needed for generating or copying UUIDs.
Q: Are UUID v4 values secure enough for passwords?
A: No. While UUID v4 is cryptographically random, it's not designed for password use. UUIDs lack sufficient entropy density for passwords, always follow a predictable format, and are typically stored as plaintext. Use a proper password generator with mixed character types instead.
Q: How do I store UUIDs in a database?
A: Most databases support native UUID types (PostgreSQL, MySQL 8.0+). Alternatively, store as CHAR(36) for the hyphenated string or BINARY(16) for compact storage. Native UUID types often offer better indexing performance.
Q: Why use UUIDs instead of auto-incrementing IDs?
A: UUIDs offer several advantages: they can be generated anywhere without coordination, don't reveal record counts or creation order, work in distributed systems, and can be generated client-side. However, they use more storage space and may be slower for indexing in some databases.
🎯 Best Practices
- Choose the Right Version:Use UUID v4 for general-purpose random IDs. Consider UUID v7 for database keys where time-ordering matters.
- Store Efficiently:Use native UUID database types when available, or BINARY(16) for compact storage instead of CHAR(36).
- Validate Format:Always validate UUIDs against the 8-4-4-4-12 pattern and check the version/variant bits when accepting external input.
- Lowercase Preference:While UUIDs are case-insensitive, prefer lowercase for consistency and better URL compatibility.
- Don't Rely on Security:UUIDs are unpredictable but not secret. Never use UUIDs as the sole security mechanism—combine with proper authentication.
- Consider Performance:For high-volume inserts, consider UUID v7 or ULID which maintain chronological ordering and are more index-friendly.
- Index Wisely:In some databases, random UUIDs can cause index fragmentation. Consider prefix indexing or sorted UUID variants if this becomes an issue.
💡 Pro Tips
- Quick Copy:Click directly on the UUID display to copy it instantly—no need to select text
- Batch Generation:Click the Generate button rapidly to create multiple UUIDs—each click creates a new unique value
- Regex Validation:Use this pattern to validate UUID v4:
^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$ - Nil UUID:The special value 00000000-0000-0000-0000-000000000000 is the nil UUID, often used as a placeholder or default value
- Case Sensitivity:UUIDs are case-insensitive per the spec, so 'A1B2C3D4' equals 'a1b2c3d4'—normalize to lowercase for consistency
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