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UUID Generator Online – Generate v4, v7, ULID, NanoID Free

Generate UUID v4, v7, ULID, and NanoID instantly. Bulk generate up to 100 IDs at once. Free online tool — no signup required.

Click "Generate UUIDs" to create random UUIDs

About UUID v4

UUID (Universally Unique Identifier) v4 generates random 128-bit identifiers. With 122 random bits, the probability of a collision is astronomically low. UUIDs are commonly used as database primary keys, session tokens, and distributed system identifiers.

Frequently Asked Questions

What are UUID versions and which should I use?
UUID v4 is random and the most commonly used for general purposes (like database IDs). UUID v7 is time-based and sortable, making it better for databases that benefit from ordering. This tool generates v4 by default. For distributed systems, v7 provides better performance because it's sortable by timestamp.
What's the probability of UUID collision?
For UUID v4 (128-bit random), the collision probability is astronomically low—you'd need to generate 5.3 × 10^36 UUIDs to have a 50% chance of one collision. In practical terms, you'll never encounter collisions for any real-world application.
UUID vs Auto-Increment: which is better?
Auto-increment is smaller and faster for single-database systems. UUIDs are better for distributed systems, microservices, and when you need unique IDs across multiple databases or servers. UUIDs don't leak information about data growth or insertion patterns.
What is ULID and how does it compare to UUID?
ULID (Universally Unique Lexicographically Sortable Identifier) is similar to UUID v7 but more compact (128 bits) and uses a different encoding. Like UUID v7, it's sortable by timestamp, making it ideal for databases. See Timestamp Converter for time-based ID generation.
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How to Use

  1. Set the number of UUIDs to generate (1-20)
  2. Choose options: uppercase, no dashes
  3. Click 'Generate UUIDs'
  4. Click on any UUID to copy, or use 'Copy All'

Common Use Cases

  • Database primary keys
  • API resource identifiers
  • Distributed system identifiers
  • Session and correlation IDs

Frequently Asked Questions

What is a UUID?
UUID (Universally Unique Identifier) is a 128-bit number used to uniquely identify information. Version 4 UUIDs are randomly generated, making collision probability astronomically low.
Are UUIDs truly unique?
While not mathematically guaranteed, UUID v4 has 2^122 possible values. The probability of generating a duplicate is essentially zero for practical purposes.
When should I use UUIDs?
Use UUIDs as database primary keys, API resource identifiers, session tokens, or any time you need a unique identifier without a central authority.