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Generate UUID v4 identifiers online. Bulk generation, uppercase/lowercase options, with or without hyphens.
Generate UUID v4 identifiers online. Bulk generation, uppercase/lowercase options, with or without hyphens.
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Click the Generate button to instantly create a new UUID v4 identifier. The generated UUID follows the standard format: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx, where each x is a random hexadecimal digit.
Choose your preferred format options: uppercase or lowercase letters, with or without hyphens. These options let you match the UUID format required by your specific system or database.
Use the bulk generation feature to create multiple UUIDs at once. Specify the quantity and generate a list of unique identifiers for batch operations, database seeding, or test data creation.
Copy individual UUIDs or the entire list to your clipboard with a single click for immediate use in your code, database queries, or configuration files.
UUIDs (Universally Unique Identifiers) are essential for distributed systems where multiple components need to generate unique identifiers independently without coordination. Unlike sequential IDs, UUIDs can be created on any machine at any time without risk of collision.
Database architects use UUIDs as primary keys to prevent enumeration attacks (where sequential IDs reveal the total number of records), enable easy data merging from multiple sources, and support distributed database architectures where records are created across different servers.
UUID v4 identifiers are generated using cryptographically secure random numbers in your browser, ensuring both uniqueness and security. The probability of generating two identical UUID v4s is astronomically small: approximately 1 in 2^122.
Software developers need test UUIDs for unit tests, mock data, API testing, and database seeding. The bulk generation feature creates properly formatted identifiers without writing custom code.
All generation happens in your browser using the Web Crypto API. No identifiers are sent to or stored on any server, making the tool suitable for generating IDs for security-sensitive applications.
When using UUIDs as database primary keys, consider the impact on index performance. In some databases (like MySQL with InnoDB), random UUIDs can cause index fragmentation. Consider UUID v7 (time-ordered) for better index locality if your database supports it.
For URL-friendly identifiers, use the no-hyphens format. This produces a 32-character hexadecimal string that works well in URLs, file names, and other contexts where hyphens might cause issues.
Always validate UUID format when accepting them as input in your applications. A valid UUID v4 has the digit 4 in the third group and 8, 9, a, or b as the first digit of the fourth group.
When bulk generating UUIDs for test data, copy the entire list and use text manipulation to insert them into SQL INSERT statements or JSON arrays.
A UUID (Universally Unique Identifier) is a 128-bit identifier formatted as 32 hexadecimal digits in five groups separated by hyphens. UUIDs can be generated independently on any machine without coordination while maintaining extremely low duplication probability. They are commonly used as database primary keys, session tokens, API identifiers, and distributed system correlation IDs.
UUID v4 uses random numbers for all fields except version and variant bits, making it the most common version. UUID v1 includes a timestamp and MAC address. UUID v3 and v5 use namespace-based hashing. UUID v7 uses a Unix timestamp prefix for time-ordered generation, improving database index performance while maintaining uniqueness.
Theoretically possible but practically impossible. UUID v4 has 122 random bits, yielding approximately 5.3 x 10^36 possible values. To reach a 50% collision probability, you would need to generate about 2.7 quintillion UUIDs. Even generating one billion per second for 85 years would not reach that threshold.
UUIDs excel in distributed systems, prevent ID enumeration attacks, enable data merging from multiple sources, and can be generated anywhere without database access. Sequential IDs are smaller (4-8 bytes vs 16 bytes) and better for index performance. Choose UUIDs for distributed generation and data privacy; sequential IDs for simpler applications.
Yes. The generator uses the Web Crypto API (crypto.getRandomValues) which provides cryptographically secure pseudo-random numbers. This means the generated UUIDs are suitable not only for general identification but also for security-sensitive applications where predictability would be a vulnerability. The randomness source is your operating system's cryptographic random number generator.
Copy the UUID and use it as a string literal. In PostgreSQL use the uuid data type, in Python use the uuid module, in Java use java.util.UUID, and in JavaScript use the string directly. When accepting UUIDs as input, always validate the format using a regex pattern.
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