UUID Generator
Generate random UUID v4 identifiers locally for databases, APIs, test data, request IDs and development workflows. Create one UUID or up to 1000 at once.
UUID settings
Choose quantity, format and output separator.
Generated UUIDs
Copy, download or edit the generated identifiers.
Quick UUID examples
What is a UUID?
UUID means Universally Unique Identifier. It is a standardized identifier format used to label records, objects, requests, users, files and other pieces of data without needing one central counter. UUIDs are common in databases, APIs, distributed systems and test data because two systems can usually generate IDs independently without coordinating every value.
What is UUID v4?
UUID v4 is the random version of UUID. It uses random bits, then sets specific version and variant bits so the identifier matches the UUID v4 format. A standard UUID v4 looks like 550e8400-e29b-41d4-a716-446655440000. The 4 in the third group identifies the UUID version.
Why developers use UUIDs
Developers use UUIDs when they need IDs that can be created before a record reaches a database, or when many systems need to create identifiers independently. UUIDs are useful for API resources, queue messages, imports, logs, test fixtures and distributed services.
UUID with or without hyphens
The standard UUID display format includes hyphens. Some systems accept compact UUIDs without hyphens, and some legacy systems prefer uppercase. Match the format your database, API, framework or test suite expects.
UUIDs in databases, APIs and test data
UUIDs are often used as database primary keys, public resource IDs, correlation IDs and test data identifiers. They are convenient when importing data or creating sample records because the ID can be generated before insertion.
UUID limitations and collision risk
UUID v4 collisions are extremely unlikely when generated with proper randomness, but not mathematically impossible. UUIDs are identifiers, not passwords or API secrets. Do not rely on a UUID as a hidden authentication token, and do not treat it as meaningful data.
Common UUID mistakes
Using UUIDs as passwords or API secrets
UUIDs are identifiers. They should not replace passwords, API keys or cryptographic secrets.
Assuming UUIDs are always sequential
UUID v4 values are random, not sequential. Do not sort them expecting creation order.
Removing hyphens when a system expects standard format
Compact UUIDs can be useful, but many validators expect the standard hyphenated format.
Mixing UUID versions without checking requirements
Different systems may expect UUID v4, UUID v7 or another version. Check the required format before generating test data.
Generating IDs with weak randomness
This tool uses browser crypto APIs and does not fall back to weak random number generation.
Treating UUIDs as meaningful data
A UUID should identify something. It should not encode business meaning, status or sensitive information.
Free online UUID generator
This UUID generator creates random UUID v4 identifiers locally in your browser. It is useful for developers, API designers, database users, testers, DevOps engineers and students who need practical identifiers for records, mock data, API examples and debugging. You can generate one UUID or bulk-generate up to 1000 values, then copy or download them as text.
The output options are designed for everyday developer workflows. Use standard lowercase UUIDs with hyphens for most systems, uppercase UUIDs for legacy tools, UUIDs without hyphens for compact formats, quoted UUIDs for quick copy-paste into code, or JSON arrays for fixtures and seed data.
Local UUID generation
UUIDs are generated locally. The tool uses crypto.randomUUID() when available and falls back to crypto.getRandomValues() with RFC 4122 UUID v4 version and variant bits. If browser crypto APIs are unavailable, generation stops and shows a warning instead of using weak randomness.
UUID Generator FAQ
What is a UUID?
A UUID is a Universally Unique Identifier, a standardized identifier format used to label records, objects, requests and other data.
What is UUID v4?
UUID v4 is a randomly generated UUID version. It uses random bits with specific version and variant bits set by the UUID standard.
Are UUIDs unique?
UUIDs are designed to be unique in practice when generated with strong randomness, but uniqueness is not mathematically guaranteed.
Can UUIDs collide?
UUID v4 collisions are extremely unlikely with proper randomness, but not impossible in a strict mathematical sense.
Is a UUID the same as a GUID?
UUID and GUID usually refer to the same kind of identifier. GUID is a common term in Microsoft ecosystems.
Should UUIDs have hyphens?
The standard UUID display format includes hyphens. Some systems accept UUIDs without hyphens, but you should match the format your system expects.
Can I generate multiple UUIDs at once?
Yes. This tool can generate between 1 and 1000 UUIDs at once.
Are UUIDs secure secrets?
No. UUIDs are identifiers, not passwords, API keys or authentication secrets.
Is my generated UUID data sent to your servers?
No. UUID generation runs locally in your browser and generated values are not uploaded.
Is this tool free?
Yes. The UUID generator is free to use and runs in your browser.