UUID/GUID Generator
Generate unique identifiers for your applications
Random UUID, suitable for most purposes
Max: 100 UUIDs
Generated UUIDs will appear here
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About Our UUID/GUID Generator
Our UUID/GUID Generator creates universally unique identifiers that you can use in your applications, databases, or any system that requires unique IDs. These identifiers are designed to be unique across both space and time, making them ideal for distributed systems where coordination is difficult.
What are UUIDs and GUIDs?
UUID (Universally Unique Identifier) and GUID (Globally Unique Identifier) are essentially the same thing - 128-bit identifiers that are extremely unlikely to be duplicated. They're standardized by RFC 4122 and are used in many computing systems to identify information without central coordination.
UUID Versions
Our generator supports all eight UUID versions:
- Version 1 (Time-based): Generated using the current timestamp and a node identifier. This version guarantees uniqueness across space and time.
- Version 2 (DCE Security): Similar to Version 1, but includes a local domain identifier for security purposes.
- Version 3 (Name-based, MD5): Generated by hashing a namespace identifier and name using MD5.
- Version 4 (Random): Generated using random or pseudo-random numbers. This is the most commonly used version and is suitable for most purposes.
- Version 5 (Name-based, SHA-1): Similar to Version 3, but uses SHA-1 hashing for better collision resistance.
- Version 6 (Reordered Time-based): An improved version of Version 1 with the timestamp bits reordered for better database indexing.
- Version 7 (Unix Timestamp-based): Uses Unix timestamp for better sorting and database performance.
- Version 8 (Custom): A customizable format that allows for application-specific implementations.
Format Options
We offer several format options to suit different requirements:
- Standard: The canonical format with hyphens (e.g., 550e8400-e29b-41d4-a716-446655440000)
- No Hyphens: Removes all hyphens for a more compact representation
- With Braces: Surrounds the UUID with curly braces, common in some systems
- URN: Formats as a Uniform Resource Name (URN) according to RFC 4122
Common Uses for UUIDs
UUIDs are used in many contexts, including:
- Database primary keys, especially in distributed systems
- Session identifiers in web applications
- Transaction IDs in financial systems
- Unique identifiers for documents or resources
- Device identification in IoT systems
- Tracking entities across different systems without coordination
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Frequently Asked Questions
How unique are UUIDs really?
UUIDs are designed to be practically unique. For Version 4 UUIDs, the probability of generating a duplicate is astronomically small - about 1 in 2^122 (or 1 in 5,316,911,983,139,663,491,615,228,241,121,378,304). To put this in perspective, you'd need to generate 1 trillion UUIDs every second for 10 billion years to have a 50% chance of generating just one duplicate.
What's the difference between UUID and GUID?
Technically, there's no difference between a UUID and a GUID - they're different names for the same concept. UUID is the term used in most standards and open systems, while GUID is Microsoft's implementation of the UUID standard. Both refer to a 128-bit value used to identify information in computer systems.
Which UUID version should I use?
For most applications, Version 4 (random) UUIDs are recommended. They're simple to generate, don't require any coordination, and have sufficient uniqueness for most purposes. Version 1 (time-based) UUIDs might be preferred in specific cases where you want to be able to sort UUIDs chronologically.
For database applications, the newer Version 6 and Version 7 UUIDs are often better choices as they provide both timestamp-based ordering and better database index locality. Version 7 is particularly recommended for new applications as it uses the Unix timestamp format which is more widely understood.
Are UUIDs secure for sensitive information?
UUIDs are not designed to be cryptographically secure or to hide information. Version 1 UUIDs contain timestamp and MAC address information that could potentially be extracted. If you need identifiers for sensitive information that shouldn't be guessable, consider using a cryptographically secure random number generator or a different approach entirely.
Can I use UUIDs as database primary keys?
Yes, UUIDs are commonly used as database primary keys, especially in distributed systems where multiple servers might be creating records simultaneously. However, be aware that they're larger than sequential integers (16 bytes vs 4 bytes) and might impact performance in very large tables due to their random nature affecting index efficiency. Many modern databases have optimizations for UUID columns.
For database performance, consider using Version 6, 7, or 8 UUIDs which are designed to be more database-friendly with better index locality than the traditional Version 4 random UUIDs.
What's the difference between the newer UUID versions (6, 7, 8)?
These versions were introduced to address limitations in the original UUID standard (RFC 4122):
- Version 6: Reorders the timestamp bits from Version 1 to make them more suitable for database indexing while maintaining the same time source.
- Version 7: Uses Unix timestamp (milliseconds since epoch) which is more widely understood and implemented across systems. This makes it ideal for distributed databases.
- Version 8: A customizable format that allows developers to implement application-specific UUID formats while maintaining compatibility with the UUID standard.
These newer versions are defined in RFC 9562, which was published in 2023 to extend the original UUID standard.