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Free UUID Generator | Generate UUID v1, v3, v4, v5 Online Tool
Generate universally unique identifiers (UUID) instantly with our free online UUID generator tool. Create UUID v1 (time-based), v3 (MD5 name-based), v4 (random), and v5 (SHA-1 name-based) identifiers. Perfect for database keys, API identifiers, distributed systems, and unique ID generation. Cryptographically secure, 100% client-side and private.
Key Features of Our UUID Generator
- Multiple UUID Versions - v1 (time-based), v3 (MD5), v4 (random), v5 (SHA-1)
- Cryptographically Secure - Uses crypto.randomUUID() for v4 generation
- Bulk Generation - Generate 5, 10, or 25 UUIDs at once
- Copy to Clipboard - One-click copy of generated UUIDs
- Download as Text - Save UUIDs to a text file
- Namespace Support - For v3 and v5 name-based UUIDs
- Real-time Generation - Auto-generate on version change
- Version Information - See details about each UUID version
- Client-Side Only - All generation happens in your browser
- 100% Free - No watermarks, no premium tiers
- No Registration - Use instantly without signup
- Offline Support - Works without internet connection
Understanding UUID (Universally Unique Identifier)
What is a UUID?
A Universally Unique Identifier (UUID) is a 128-bit number used to uniquely identify information in computer systems. The standard format consists of 32 hexadecimal digits, displayed in 5 groups separated by hyphens: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. UUIDs are defined by RFC 4122.
Why Use UUIDs?
UUIDs guarantee uniqueness across systems without central coordination. They can be generated offline without contacting a database, are safe for use in distributed systems and APIs, and cannot be sequentially guessed (unlike auto-increment IDs). The probability of duplicate UUID v4 is astronomically low (1 in 2^122).
UUID Versions Explained
UUID v1 (Time-based)
UUID v1 combines a timestamp (60 bits), a clock sequence (14 bits), and a node identifier (48 bits, usually the MAC address). These UUIDs are time-ordered, making them good for database indexing but potentially exposing the generating machine's identity and time.
UUID v3 (Name-based with MD5)
UUID v3 generates deterministic UUIDs from a namespace and name using MD5 hashing. The same namespace and name always produce the same UUID. This is useful for generating consistent identifiers for DNS names, URLs, or object IDs.
UUID v4 (Random)
UUID v4 is generated from random or pseudo-random numbers. It's the most commonly used version due to its simplicity and sufficient randomness for most applications. 122 bits of the UUID are randomly generated, providing excellent uniqueness.
UUID v5 (Name-based with SHA-1)
UUID v5 is similar to v3 but uses SHA-1 hashing instead of MD5. SHA-1 provides better collision resistance than MD5, making v5 the preferred choice for name-based UUID generation.
Common Use Cases for UUIDs
- Database Primary Keys - Unique identifiers for distributed database records
- API Resource Identifiers - Track resources across different systems
- Session Tokens - Generate unique session identifiers
- File Names - Prevent filename collisions in upload systems
- Transaction IDs - Track transactions in distributed systems
- Entity Identifiers - Identify entities across microservices
UUID Generator
Generate universally unique identifiers (UUID v1, v3, v4, v5) instantly. Perfect for database keys, API identifiers, and distributed systems.
UUID Generator
Generate unique UUIDs for your applications. Choose from different versions based on your needs.
Random UUID (most common) • General purpose, unique identifiers • Speed: Very Fast
Multiple Versions
Support for UUID v1, v3, v4, and v5.
Cryptographically Secure
Uses crypto.randomUUID() for secure v4 generation.
Bulk Generation
Generate up to 25 UUIDs at once.
Client-Side Only
All generation happens in your browser.
How to Use UUID Generator - Complete Guide
Select Version
Choose the UUID version that fits your needs (v4 is most common).
Generate UUID
Click generate to create a unique UUID instantly.
Copy or Download
Copy to clipboard or download as a text file.
UUID Versions Comparison
| Version | Method | Uniqueness | Best For |
|---|---|---|---|
| v1 | Time + MAC address | Unique | Legacy systems |
| v3 | MD5 + namespace | Deterministic | Name-based |
| v4 | Random | Very High | General purpose |
| v5 | SHA-1 + namespace | Deterministic | DNS, URLs |
What is a UUID?
A Universally Unique Identifier (UUID) is a 128-bit number used to uniquely identify information in computer systems. The standard format consists of 32 hexadecimal digits, displayed in 5 groups separated by hyphens: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
Why use UUIDs?
- Guaranteed uniqueness across systems without central coordination
- Can be generated offline without contacting a database
- Safe for use in distributed systems and APIs
- No sequential guessing (unlike auto-increment IDs)
UUID Format & Structure
UUID Format
xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
- • 32 hexadecimal digits (0-9, a-f)
- • 5 groups separated by hyphens
- • Total length: 36 characters (including hyphens)
- • Total bits: 128 bits
Frequently Asked Questions
Which UUID version should I use?
For most applications, UUID v4 (random) is recommended. It provides sufficient randomness and uniqueness. Use v1 if you need time-ordered IDs, or v5 for deterministic name-based UUIDs.
Are UUIDs truly unique?
The probability of duplicate UUID v4 is astronomically low (1 in 2^122). You would need to generate billions of UUIDs per second for 100 years to have a 50% chance of a collision. For practical purposes, they are guaranteed to be unique.
What's the difference between UUID v3 and v5?
Both generate name-based UUIDs using a namespace and name. v3 uses MD5 hashing (older, 128-bit), while v5 uses SHA-1 (newer, 160-bit). v5 is generally preferred over v3.
Is this generator secure?
Yes! Our generator uses the browser's built-in crypto.randomUUID()method for v4, which is cryptographically secure. All generation happens locally in your browser.
Can I use UUIDs as database primary keys?
Yes, UUIDs are excellent for database primary keys, especially in distributed systems. However, they can impact performance due to their size (16 bytes vs 4 bytes for integers) and randomness (leading to index fragmentation). Consider using sequential UUIDs (v1 or v7) for better database performance.
Can I use this tool offline?
Yes! Once the page loads, our UUID Generator works completely offline. Perfect for when you don't have an internet connection.
What is the difference between UUID and GUID?
Technically, there is no difference. GUID (Globally Unique Identifier) is Microsoft's implementation of the UUID standard. Both refer to 128-bit unique identifiers and are interchangeable in practice.
Why Use Our UUID Generator?
Multiple Versions
Support for UUID v1, v3, v4, and v5.
Cryptographically Secure
Uses crypto.randomUUID() for secure v4 generation.
Bulk Generation
Generate up to 25 UUIDs at once.
Client-Side Only
All generation happens in your browser.
No Registration
Use instantly without any signup.
Free Forever
Completely free with no hidden costs.
Pro Tips for UUID Generation
- • Use UUID v4 for most applications - it's random and sufficiently unique
- • Use UUID v1 if you need time-ordered IDs for database indexing
- • Use UUID v5 for deterministic IDs based on names (same input = same output)
- • Never store sensitive information directly in UUIDs - they're not encrypted
- • For bulk generation, use the 5, 10, or 25 button to save time
- • Download UUIDs as text files for offline reference or batch processing
UUID Generator | v1 (Time-based) | v3 (MD5) | v4 (Random) | v5 (SHA-1)
Processing: 100% client-side • Cryptographically secure • Complete privacy
Standard: RFC 4122 • Format: 8-4-4-4-12 hexadecimal digits
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