UUID Generator

What is UUID and Why is it Needed?

UUID (Universally Unique Identifier) or GUID (Globally Unique Identifier) is a 128-bit identifier guaranteeing global uniqueness without central coordination. UUID is represented as 32 hexadecimal digits in the format: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. The probability of generating two identical UUIDs is so small (1 in 2^122) that it's practically impossible.

UUID Versions and Their Differences

There are several UUID versions, each designed for specific use cases:

UUID v1 (Timestamp-based)

Generated based on current time and MAC address of the network card. Guarantees uniqueness but reveals the creation time and hardware address, which may be undesirable for security reasons.

UUID v4 (Random)

Generated using a cryptographic random number generator. The most popular version due to simplicity and absence of dependence on hardware or time. Recommended for most use cases.

UUID v5 (Name-based with SHA-1)

Generated based on namespace and name using SHA-1 hashing. Creates deterministic UUIDs — the same input always produces the same UUID.

Where are UUIDs Used?

• Database Primary Keys — UUIDs allow creating unique identifiers without centralized coordination, ideal for distributed systems and microservices
• Session and Request Identifiers — Tracking user sessions, API requests, and transactions in logging and monitoring systems
• File and Object Naming — Generating unique names for uploaded files, temporary data, cache keys
• Distributed Systems — Identifying entities in microservices, message queues (Kafka, RabbitMQ), event sourcing
• Testing and Development — Generating unique test data, user IDs, product IDs for development and testing environments
• API Integration — Creating idempotency keys to prevent duplicate operations, correlation IDs for request tracing

Advantages of Using UUID

• No need for centralized identifier generation — each node can generate UUIDs independently
• Guaranteed global uniqueness without coordination between systems
• Possibility of offline generation without database access
• Standardization — UUID supported by all modern programming languages and databases
• Security — random UUIDs are unpredictable, unlike sequential IDs

Disadvantages and Limitations

• Large size (128 bits vs 32-64 bits for integers) increases storage requirements
• Reduced indexing performance in databases compared to sequential identifiers
• Less convenient for humans — difficult to remember and manually enter
• UUID v1 reveals MAC address and timestamp, which may be a privacy issue

Best Practices for Using UUID

• Use UUID v4 for most cases where you need random unique identifiers
• For deterministic generation (same input = same UUID), use UUID v5
• In databases with UUID primary keys, use specialized types (uuid in PostgreSQL) instead of strings
• Consider using UUIDv7 (time-ordered) for better database indexing performance
• Store UUIDs in binary format (16 bytes) instead of text (36 characters) to save space
• Use bulk generation when you need to create many identifiers at once

UUID Validation

Our tool includes UUID validation that checks format correctness, version, and variant compliance with RFC 4122. This is useful for verifying user input, debugging API integration, or checking identifier generation correctness in your application.

Frequently Asked Questions