UUID Generator
Generate unique UUID v4 identifiers instantly — one or in bulk
UUID Validator
What is UUID Generator?
A UUID (Universally Unique Identifier) is a 128-bit identifier standardised by RFC 4122, formatted as 32 hexadecimal characters grouped into five sections separated by hyphens: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. Version 4 UUIDs are generated using random numbers, which makes the probability of two UUIDs ever colliding astronomically small — roughly 1 in 5.3 × 10³⁶. This makes them the go-to identifier for distributed systems where a central auto-increment counter is impractical. Our free UUID Generator produces cryptographically random v4 UUIDs instantly in your browser. You can generate a single UUID for a one-off need, or produce hundreds at once for seeding databases, creating test fixtures, or provisioning resources in bulk. Every UUID is generated using the browser's built-in crypto.randomUUID() API, ensuring genuine randomness without relying on any external server. Use them as primary keys in PostgreSQL or MySQL, document IDs in MongoDB, resource identifiers in REST APIs, session tokens, correlation IDs for distributed tracing, or asset filenames in cloud storage.
How to Use UUID Generator
- 1
Choose How Many
Enter the number of UUIDs you need — from a single one to hundreds at once. The default is 1 for quick single-use needs.
- 2
Click Generate
The tool uses your browser's crypto.randomUUID() API to produce cryptographically random version 4 UUIDs. Each one is guaranteed to be unique.
- 3
Copy and Use
Copy a single UUID with one click, or copy all generated UUIDs to your clipboard as a newline-separated list to paste directly into a SQL script, JSON file, or spreadsheet.
Use Cases
Database Primary Keys in Distributed Systems
In microservices and distributed architectures, auto-increment IDs create coordination problems — two services cannot independently assign IDs without conflict. UUIDs solve this: each service generates its own IDs locally with no central authority needed. This tool lets developers quickly generate UUIDs to use as primary keys when designing schemas or writing migration scripts.
Seeding Test Databases with Realistic Data
When writing integration tests or populating a staging database, you need a large number of realistic, non-colliding identifiers. Generate hundreds of UUIDs here, paste them into your seed script or JSON fixture file, and your test data will have properly formatted IDs that match production format exactly.
Correlation IDs for Distributed Tracing
When a request flows through multiple microservices, attaching a unique correlation ID to every log entry lets you trace the entire request journey across services. Engineers generate a UUID at the API gateway layer and forward it in a custom header (e.g., X-Correlation-ID) so every service logs the same ID for that transaction.
Features
Cryptographically Random v4 UUIDs
Uses the browser's built-in crypto.randomUUID() — the same source of randomness used in operating systems — ensuring genuine unpredictability for security-sensitive use cases.
Bulk Generation
Generate 1 to 1,000 UUIDs in a single click. Perfect for seeding a database, creating test fixtures, or provisioning cloud resources in batch.
Copy Single or All
Copy any individual UUID from the list, or copy all generated UUIDs at once as a newline-separated list ready to import into a script or spreadsheet.
No Server, No Storage
UUIDs are generated entirely in your browser. Nothing is logged, stored, or transmitted — your identifiers remain completely private.
Frequently Asked Questions
A UUID (Universally Unique Identifier) is a standardised 128-bit number used to uniquely identify information without a central registration authority. Version 4 (v4) UUIDs are generated using random or pseudo-random numbers rather than being derived from a MAC address (v1) or a namespace hash (v3, v5). V4 is the most commonly used version because it requires no input data and has extremely low collision probability.
In theory, yes — UUIDs are not mathematically guaranteed to be unique. In practice, a collision is so astronomically unlikely that it is treated as impossible. With v4, the probability of generating a duplicate among 1 billion UUIDs is approximately 1 in 2.71 × 10¹⁸. At real-world generation rates, you would need to produce trillions of UUIDs per second for hundreds of years before a collision became likely.
Yes, essentially. GUID (Globally Unique Identifier) is Microsoft's name for the same concept, used in .NET and Windows development. GUIDs follow the same RFC 4122 standard and format as UUIDs. The terms are used interchangeably, though "UUID" is the standard term in most modern documentation.
UUIDs are excellent primary keys in distributed systems where multiple services or nodes generate IDs independently. The trade-offs: they are larger (16 bytes vs 4 bytes for a 32-bit integer), can fragment B-tree indexes in databases like MySQL if inserted in random order, and are harder to read in logs. For single-server applications, auto-increment integers are often simpler. For distributed systems, UUIDs or ULIDs are strongly preferred.
UUID v1 is generated from the current timestamp combined with your machine's MAC address. This means two v1 UUIDs generated close together are sequential and partially predictable — a potential privacy and security concern since they encode your network interface. UUID v4 is generated purely from random numbers, making it unpredictable and safe to expose publicly, which is why v4 is the default choice for most web applications.
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