What is UUID?
A UUID (Universally Unique Identifier), also known as a GUID (Globally Unique Identifier), is a 128-bit label used to uniquely identify resources in computer systems. Defined by RFC 4122, UUIDs follow a standardized format of 32 hexadecimal digits displayed in five groups separated by hyphens (e.g., 550e8400-e29b-41d4-a716-446655440000). Version 4 UUIDs, which this tool generates, use cryptographically strong random numbers, providing approximately 5.3 x 10^36 possible values. This makes the probability of generating a duplicate effectively zero, even across billions of IDs generated independently by different systems.
How to Use This Tool
Set the number of UUIDs you want to generate (up to 100 at once) and click "Generate." Toggle the "Uppercase" option if your system requires uppercase hexadecimal characters. All generated UUIDs appear in a list that you can copy with a single click. Each batch is generated fresh using your browser's crypto.getRandomValues API, ensuring true cryptographic randomness.
Common Use Cases
- Generating primary keys for database records in PostgreSQL, MongoDB, MySQL, or any data store
- Creating unique correlation IDs for distributed tracing across microservices and message queues
- Assigning unique identifiers to API resources, file uploads, or user sessions
- Generating idempotency keys for payment processing, webhook delivery, and retry-safe API operations
Why Use a Client-Side Tool?
UUIDs are often used as security-sensitive identifiers for sessions, tokens, and database records. Generating them on a remote server means a third party could potentially log or intercept your IDs. Our tool generates UUIDs entirely in your browser using the Web Crypto API, which provides the same cryptographic quality as server-side libraries. No UUIDs are transmitted, stored, or logged anywhere. This makes it safe to generate IDs for production databases, security tokens, and any system where ID predictability would be a vulnerability.
Frequently Asked Questions
What is the difference between UUID v1 and UUID v4?
UUID v1 is generated using the current timestamp and the device's MAC address, which means it can reveal when and where it was created. UUID v4 is generated entirely from random numbers, providing no information about its origin. Version 4 is the most widely used type because it offers better privacy and simplicity.
Can two UUID v4 values ever be the same?
While theoretically possible, the probability is astronomically low. With 122 random bits, you would need to generate approximately 2.7 x 10^18 UUIDs before there is a 50% chance of a single collision. For all practical purposes, UUID v4 values are unique.
Should I use UUIDs or auto-incrementing integers as database primary keys?
UUIDs are ideal for distributed systems where multiple nodes create records independently, for exposing IDs in public APIs (since they are not guessable), and for merging data from different sources. Auto-incrementing integers are more storage-efficient and produce better index locality. The right choice depends on your architecture and security requirements.