What is the difference between UUID v4 and other UUID versions?

UUID v4 is randomly generated and has no embedded information about the generating machine, time, or namespace — it is the most common choice for general-purpose unique identifiers. UUID v1 includes the machine's MAC address and current timestamp, which creates both privacy concerns and ordering properties. UUID v7, a newer standard gaining adoption, is timestamp-ordered making it more efficient for database indexes than random v4, but v4 remains the most universally supported version.

Can I use UUIDs as primary keys in PostgreSQL and MySQL?

Yes, both PostgreSQL (with the uuid type) and MySQL (with CHAR(36) or the binary(16) pattern for efficiency) fully support UUID primary keys. PostgreSQL's native uuid type stores UUIDs as 16 bytes rather than 36 characters, making storage and index operations more efficient than storing the hyphenated string. For MySQL, random UUIDs can cause index fragmentation due to random insertion order — consider UUID v7 or a sequential UUID strategy if write-heavy workloads are a concern.

How do I quickly copy a generated UUID to use in my code?

The copy button next to each generated UUID copies it to your clipboard immediately so you can paste directly into your editor or terminal. When generating in bulk, most outputs include a copy-all option that places the full list on the clipboard separated by newlines, ready to paste into a JSON array or SQL VALUES clause. In JavaScript, you can also call crypto.randomUUID() directly in the browser console or Node.js 14.17+ without needing any external library.

Do generated UUIDs contain any personally identifiable information?

UUID v4 is purely random and contains no information about the user, device, IP address, or time of generation — unlike UUID v1 which embeds the MAC address and creation timestamp. This makes v4 safe to expose in public URLs and API responses without leaking operational details about your infrastructure. However, the UUID itself can become a correlating identifier if linked to user accounts in your database, so treat stored UUIDs with the same access controls as other user identifiers.

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UUID Generator

Generate cryptographically secure UUIDs (v4). Instant and free.

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How to Use

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Configure UUID options

Select UUID version (v1 time-based or v4 random). Choose output format — single UUID, multiple UUIDs, uppercase, or with/without hyphens.

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Generate UUID(s)

Click Generate to create cryptographically random UUIDs. Each UUID is globally unique — the probability of collision is astronomically low.

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Copy and use

Click Copy to grab the generated UUID(s). Perfect for database primary keys, API request IDs, session tokens, or any unique identifier need.

What is UUID Generator?

UUID Generator is a browser tool that produces cryptographically random UUID v4 identifiers using the browser's native crypto.randomUUID() API. It solves the need for unique, collision-resistant IDs in database design, API development, and distributed systems without installing any packages or running a backend. Developers, database architects, and software engineers use UUID generation when designing schemas or seeding test data.

Why use UUID Generator?

Using the browser's built-in crypto.randomUUID() function means the generated UUIDs are cryptographically secure and meet RFC 4122 standards — not pseudo-random values that could collide in production systems. Bulk UUID generation lets you produce dozens or hundreds of unique identifiers at once and copy them straight to your clipboard, saving the repetitive effort of calling a UUID library manually. The tool requires no signup, no API key, and leaves no history on a server.

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devicesWorks everywhere — Any modern browser on desktop, tablet, or mobile.

How it works

Database engineers use bulk UUID generation to seed primary keys for test fixtures and staging data before running migration scripts. Frontend developers generate UUID v4 values to assign temporary client-side IDs to list items in React or Vue before the server confirms persistence. QA testers use generated UUIDs as unique correlation IDs in API request headers when load testing distributed microservices.

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Pro Tip

UUID v4 is statistically unique enough for virtually all production use cases — with 2^122 possible values, the probability of a collision across a billion generated IDs is astronomically small, so you do not need sequential UUIDs unless your database index performance requires it. Copy multiple UUIDs at once using the bulk generation feature and paste them directly into SQL INSERT statements or JSON fixtures to avoid manual formatting.

Frequently Asked Questions

Yes, the generator uses crypto.randomUUID() which draws from the browser's cryptographically secure random number generator, the same source used for TLS key generation. UUID v4 has 122 bits of randomness, making the probability of collision so infinitesimally small that it is not a practical concern even when generating millions of IDs. This is safe for production use as primary keys, correlation IDs, and session identifiers.

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