Our free UUID (Universally Unique Identifier) generator creates unique identifiers instantly for use in databases, applications, APIs, and any system requiring unique IDs. Generate version 4 UUIDs that are guaranteed to be globally unique with one click.
A UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify information in computer systems. UUIDs are designed to be globally unique without requiring a central registration authority. The standard UUID format is represented as 32 hexadecimal digits displayed in five groups separated by hyphens, in the form 8-4-4-4-12, for example: 550e8400-e29b-41d4-a716-446655440000.
Our generator creates version 4 UUIDs, which are randomly generated. The probability of generating duplicate UUIDs is so low (approximately 1 in 5.3 x 10^36) that it's considered negligible for practical purposes. This makes UUIDs perfect for distributed systems where multiple entities need to create unique identifiers without coordination.
Using our UUID generator is extremely simple. Click the "Generate UUID" button to instantly create a new universally unique identifier. The UUID will appear in the text field above in the standard format (xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx). The "4" in the third group indicates this is a version 4 UUID.
Once generated, click the "Copy UUID" button to copy the identifier to your clipboard. You can then paste it directly into your code, database, configuration file, or wherever you need a unique identifier. Generate as many UUIDs as you need - each one will be unique.
Database Primary Keys: UUIDs are excellent for primary keys in distributed databases. Unlike auto-incrementing integers, UUIDs can be generated independently by different database nodes without conflicts. This is crucial for microservices architectures, database replication, and systems that need to merge data from multiple sources.
API Development: REST APIs often use UUIDs as resource identifiers in URLs (e.g., /api/users/550e8400-e29b-41d4-a716-446655440000). UUIDs prevent enumeration attacks where attackers try sequential IDs to access unauthorized resources, and they don't reveal information about the total number of resources.
Session Management: Web applications use UUIDs for session tokens, ensuring each user session has a unique, unpredictable identifier. This prevents session hijacking and provides better security than sequential session IDs.
File Naming: When users upload files or systems generate temporary files, UUIDs ensure unique filenames even in distributed systems. This prevents file overwrites and naming conflicts.
Transaction IDs: Financial systems and e-commerce platforms use UUIDs for transaction tracking, order numbers, and payment reference codes. The uniqueness guarantees no transaction conflicts across different systems or time zones.
Message Queue Systems: Distributed messaging systems like RabbitMQ, Kafka, and AWS SQS use UUIDs for message IDs, correlation IDs, and request tracing in microservices architectures.
There are several UUID versions defined in RFC 4122, each with different generation methods. Our tool generates version 4 UUIDs, the most commonly used variant. Here's an overview of the main versions:
Version 1 (Time-based): Generated using the current timestamp and MAC address. While unique, these UUIDs can reveal information about when and where they were created, which may be a privacy concern.
Version 4 (Random): Generated using random or pseudo-random numbers. This is what our tool creates. Version 4 UUIDs are completely random (except for version bits) and reveal no information about their creation.
Version 5 (Name-based SHA-1): Generated by hashing a namespace identifier and name. These are deterministic - the same input always produces the same UUID, which is useful for creating consistent identifiers from specific inputs.
UUIDs vs Auto-increment IDs: Traditional auto-incrementing integers (1, 2, 3...) are simple but have limitations. They're sequential, predictable, and require database coordination. UUIDs can be generated anywhere without coordination, work better in distributed systems, and don't reveal information about your data volume. However, integer IDs are smaller and slightly faster for database indexing.
UUIDs vs MongoDB ObjectIDs: MongoDB's ObjectID is a 12-byte identifier that includes a timestamp and machine identifier. While smaller than UUIDs, they're less standardized and specific to MongoDB. UUIDs are universal and work across any system or database.
UUIDs vs Random Strings: While you could generate random strings, UUIDs follow a standard format recognized globally. They have a specified structure, version information, and variant bits that ensure compatibility across different systems and programming languages.
A UUID consists of 128 bits (16 bytes) typically displayed as 32 hexadecimal digits. The standard format groups these as 8-4-4-4-12 characters separated by hyphens. In version 4 UUIDs, 6 bits are fixed (version and variant indicators), while 122 bits are random. This provides 2^122 possible UUIDs (approximately 5.3 x 10^36).
The third group's first digit is always "4" indicating version 4. The fourth group's first digit is always one of "8", "9", "a", or "b" indicating the UUID variant. These fixed bits ensure RFC 4122 compliance while maintaining extremely high uniqueness probability.
Our UUID generator uses JavaScript's Math.random() for generation. For cryptographic applications requiring even higher security, consider using the Web Crypto API's getRandomValues() method, though Math.random() is sufficient for typical UUID use cases.
All UUID generation happens entirely in your browser using client-side JavaScript. We don't store, transmit, or log any of the UUIDs you generate. The UUIDs never leave your device unless you explicitly copy and use them. This tool works completely offline once the page is loaded, ensuring maximum privacy and security. Generate as many UUIDs as you need with complete confidence in your privacy.