UUID Generator
Generate random UUID v4 identifiers instantly. Copy single or bulk UUIDs for databases, APIs, and distributed systems.
Our free UUID Generator creates random version-4 UUIDs (Universally Unique Identifiers) that you can copy with one click and use as database primary keys, API request IDs, session tokens, file names, or any identifier that… Paste or type your input above; results update immediately. The tool runs in your browser and we don't store your data.
About This Calculator
Our free UUID Generator creates random version-4 UUIDs (Universally Unique Identifiers) that you can copy with one click and use as database primary keys, API request IDs, session tokens, file names, or any identifier that must be globally unique. Each UUID is a 128-bit value formatted as 32 hexadecimal digits in five groups (8-4-4-4-12), for example 550e8400-e29b-41d4-a716-446655440000. Version 4 UUIDs are generated from cryptographically strong random numbers, making collisions virtually impossible — the probability of generating two identical UUIDs is roughly 1 in 5.3 x 10^36. Generate a single UUID or bulk-generate multiple UUIDs at once for seeding databases or writing test fixtures.
How It Works
The generator uses your browser's built-in cryptographic random number generator (crypto.getRandomValues) to produce 128 bits of randomness. It then formats the result as a UUID v4 string, setting the version nibble to 4 and the variant bits to the RFC 4122 standard. The output follows the canonical 8-4-4-4-12 format. Each generated UUID is independent — no sequence, no timestamp, and no hardware identifier is embedded, which makes v4 UUIDs fully anonymous and suitable for privacy-sensitive applications. Everything runs locally; no network request is made.
How to Use
- Enter your values in the calculator fields above
- Click the calculate button or let the calculator auto-update
- Review your results instantly
- Adjust values as needed to see different scenarios
Frequently Asked Questions
What is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit label standardized by RFC 4122, designed to be unique across all devices and all time without a central authority. It is written as 32 hex digits in five groups separated by hyphens. UUIDs are used whenever you need an ID that will not collide with IDs generated by other systems.
What is the difference between UUID versions?
UUID v1 uses the current timestamp and the device's MAC address (partially identifiable). UUID v4, which this tool generates, uses pure random numbers (fully anonymous). UUID v5 uses a namespace plus a name hashed with SHA-1. UUID v7 (newer) combines a Unix timestamp with randomness for sortable, time-ordered IDs. Version 4 is the most widely used for general-purpose unique IDs.
Can two UUIDs ever collide?
In theory, yes, but the probability is astronomically low. UUID v4 provides 122 bits of randomness, yielding about 5.3 x 10^36 possible values. You would need to generate roughly 2.7 x 10^18 UUIDs (2.7 quintillion) before having a 50% chance of a single collision. For all practical purposes, collisions will not happen.
Where are UUIDs commonly used?
Database primary keys (PostgreSQL has a native UUID type), distributed microservice request tracing, user session identifiers, API idempotency keys, file and asset naming, message queue deduplication, and OAuth state parameters. Anywhere you need a unique ID without coordinating with a central server, UUIDs are the standard choice.
Is UUID the same as GUID?
Yes. GUID (Globally Unique Identifier) is Microsoft's term for the same concept. The format and generation algorithms are identical. In .NET code you will see "Guid.NewGuid()" which produces a UUID v4.
Is this generator secure and private?
Yes. UUIDs are generated using your browser's crypto.getRandomValues API, which provides cryptographically strong randomness. No UUIDs are sent to any server. The tool works offline once the page is loaded.
Why Use Our Free UUID Generator Online?
Our UUID Generator runs in the browser so you can format, convert, or generate without sending data to our servers. No account needed—paste or type, get your result. We offer more dev tools (JSON, Base64, JWT, UUID, timestamps, and more) in the list below.