UUID Generator
Generate universally unique identifiers for databases, APIs, tests, and distributed systems. The backend generates UUID v7 by default and supports v4 or v6 through simple input or JSON configuration.
Identifier Version Legend
Generates standards-based UUID strings.
Defaults to UUID v7 for time-sortable modern identifiers.
Supports UUID v4 random IDs and UUID v6 time-ordered IDs.
Accepts simple version hints such as v4, v6, v7, 4, 6, or 7.
Useful for database primary keys, API examples, fixtures, and logs.
How to Use
Click Generate to create a UUID v7 by default
Choose v4, v6, or v7 if the UI exposes version selection
Copy the generated UUID
Use it in test data, records, API examples, or migrations
Backend Development
- Create database identifiers
- Generate API request IDs
- Seed test fixtures
Distributed Systems
- Create globally unique event IDs
- Generate sortable UUID v7 identifiers
- Avoid centralized integer ID allocation
Developer Workflows
- Databases
- REST APIs
- Event logs
- Test fixtures
UUID v7 is often a better default for databases than v4 because it is time-sortable and improves index locality.
UUID v4 is random and widely supported, but random insertion can fragment ordered indexes at high write volume.
Use UUIDs when IDs must be generated independently across multiple systems.
Prefer UUID v7 for new database-backed systems that need roughly chronological ordering.
Use UUID v4 when maximum compatibility with older systems or libraries is required.
Do not derive security decisions from the secrecy of a UUID unless it was generated with appropriate randomness.
Frequently Asked Questions
Find answers to common questions about our tools and services.
Understanding UUID Generator
A Universally Unique Identifier (UUID) is a 128-bit label used for identifying resources in computer systems. Standardized by the Internet Engineering Task Force (IETF) in RFC 4122 (and later expanded in RFC 9562), a UUID is represented as 32 hexadecimal digits displayed in five groups separated by hyphens (8-4-4-4-12 format), totaling 36 characters including the hyphens. The fundamental benefit of UUIDs is that they can be generated independently across distributed systems without coordination with a central authority. This decentralization eliminates the bottleneck of centralized counter systems and guarantees that the probability of duplicate IDs being generated is mathematically negligible.
The evolution of UUID standards has produced several versions tailored to specific use cases. Version 4 (v4) is the most widely adopted and is composed almost entirely of random bits (122 of the 128 bits are random). While v4 is excellent for generic application identifiers and correlation IDs, it suffers from a major drawback in database indexing. B-tree indexes, which are the default for primary keys in databases like PostgreSQL, MySQL, and SQL Server, rely on sorted order. Inserting completely random UUID v4 values leads to severe index page fragmentation, high disk I/O, and index "thrashing" as data volume grows, drastically reducing database write throughput.
To address B-tree indexing bottlenecks, modern system architectures prefer UUID Version 7 (v7). UUID v7 combines temporal information with high entropy, reserving the most significant 48 bits for a Unix epoch timestamp in milliseconds, followed by version and variant bits, and 74 bits of cryptographically secure random data. This creates a time-ordered, lexicographically sortable identifier. When a database inserts UUID v7 primary keys, they are appended to the end of the index structure in roughly chronological order, maintaining spatial locality, preventing page splits, and maximizing B-tree write performance, all while keeping the global uniqueness guarantee.
This UUID Generator provides developer-focused access to the main identifier variations, supporting v4, v6 (an alternative time-ordered scheme derived from Gregorian timestamps), and the recommended v7. It operates instantly through standard API requests, allowing developers to generate single IDs for staging runs, script mocks, event logging, or configuration files. By utilizing the structured metadata and clean monospace representation, users can copy unique values to their clipboards with a single click. The tool ensures a clean, fast experience for modern backend engineering, API prototyping, and system testing.