Free UUID generator

A UUID (Universally Unique Identifier) is a 128-bit identifier standardized by the IETF in RFC 9562. It is designed to be unique across both space and time — meaning no two UUIDs generated on different machines, at different moments, should ever collide. A UUID looks like this: c8e528c2-cea2-4b87-85d4-4ceb3ce8f57f. That 36-character string is the canonical form, written as five hyphen-separated groups of hexadecimal digits.

The random UUID generator on this page produces version 4 UUIDs — the most common type. A v4 UUID is entirely random, with 122 bits of entropy drawn from your browser's cryptographic random source. This makes it suitable for session tokens, database primary keys, cache keys, and any scenario where you need a practically guaranteed-unique identifier without coordinating with a central authority.

Why so many versions? The UUID generator v4 is the default because randomness is simple and universally applicable. But different use cases demand different properties. A v1 UUID generator embeds a timestamp and a network node identifier, which makes it sortable by generation time — but also leaks the machine that created it. A v7 UUID generator puts a Unix timestamp in the leading bits, giving you chronological ordering without the privacy trade-off. A v5 UUID generatortakes a name and a namespace and produces a deterministic, SHA-1-based identifier — the same input always yields the same UUID, which is exactly what you want for consistent resource naming.

When people search for an online UUID generator or an online UUID generator tool, they usually need one of three things: a quick UUID for a test fixture, a primary key for a database row, or a unique reference for an API resource. This tool covers all three. The single-generator mode produces one UUID at a time, ideal for copy-paste into a config file or a test script. The bulk UUID generator mode creates up to 100,000 values in a single batch, exported as TXT, CSV, JSON, or SQL — perfect for seeding a database or generating fixture data for development.

Every UUID generated here is created client-side using the Web Crypto API (crypto.getRandomValues). No value ever leaves your browser. There is no server-side log, no analytics ping, no third-party tracker. When you use a free UUID generator that runs entirely in your browser, you get both privacy and speed — the UUID is ready the instant you click Generate.

The UUID analyzer is the companion tool that lets you paste any UUID and inspect its internal structure. It tells you the version, variant, embedded timestamp, entropy count, and node field. This is invaluable when debugging a v1 UUID that seems to be tied to a specific machine, or when confirming that a v7 UUID carries the timestamp you expect.

Which UUID version should you use?

v4 (random) is the safe default for almost every use case — API keys, session IDs, correlation IDs, and any identifier where you do not need ordering or determinism. v7 (Unix time-ordered) is the modern choice for database primary keys, because the timestamp prefix keeps inserts sequential and B-tree indexes from fragmenting. v1 (Gregorian time) and v6 (reordered time) are mostly of historical interest; v1 leaks the generating host's node address and v6 is a niche format with limited library support. v3 and v5 (name-based) are deterministic — the same namespace and name always produce the same UUID — making them useful for stable resource identifiers in URL shortening, XML publishing, and namespace-scoped naming.

What makes a UUID version 4 different from a version 7?

A random UUID generator online that produces v4 values creates 122 bits of pure randomness, with the version nibble set to 4 and the variant nibble set to RFC 4122. The result is unordered — if you generate a thousand v4 UUIDs, they will not sort in any meaningful temporal sequence. A v4 UUID generator is ideal when you need unpredictability, such as for security tokens or random identifiers that should not reveal creation order.

A UUID generator version 7 flips the layout upside-down. The 48-bit Unix millisecond timestamp occupies the most significant bits, followed by a 4-bit version number, a 12-bit counter, and 62 bits of randomness. The result is a UUID that sorts chronologically — new values always compare greater than old values — while still being 128-bit random identifiers. This is why v7 is rapidly becoming the default for database keys in PostgreSQL, MySQL, SQLite, and MongoDB.

Is the free UUID generator really free?

Yes. There is no API key, no rate limit, no account signup, and no usage tracking. The short UUID generator label is sometimes used for truncated identifiers, but this tool produces full RFC 9562 UUIDs — every bit, every hyphen, every character. The page is static HTML and JavaScript; it can be bookmarked, shared, or used offline once loaded. The random UUID generator online runs entirely in your browser, so you can generate UUIDs on an airplane, on a locked-down corporate network, or on a machine with no internet connection at all — as long as the page loaded once.

Common use cases for UUIDs

Database primary keys: UUIDs replace auto-increment integers, preventing enumeration attacks and making sharding and replication trivial. Distributed systems: when multiple services generate identifiers independently, UUIDs guarantee global uniqueness without a central coordinator. API design: UUIDs in URLs prevent IDOR (insecure direct object reference) attacks that target sequential numeric IDs. Testing and development: a bulk UUID generator produces thousands of test rows in seconds. Content management: deterministic v5 UUIDs let you generate stable identifiers for content slugs, category names, or taxonomy terms that must remain consistent across deployments.

UUID security considerations

Not all UUIDs are created equal from a security perspective. A v1 UUID generator exposes the MAC address of the generating machine — in practice, a random node is used here, but the format still carries a timestamp that reveals when the UUID was created. A v4 UUID generator reveals nothing except randomness. A v7 UUID generator reveals the generation timestamp, which is often desirable for database keys but should be avoided when you need unguessable identifiers. Never use a UUID as a password substitute, a cryptographic nonce, or a session secret — UUIDs are identifiers, not secrets.

This tool generates UUIDs using the Web Crypto API'scrypto.getRandomValues method, which is cryptographically strong and suitable for security-sensitive identifiers. The page itself is served as static files — there is no backend that could log, intercept, or tamper with your UUIDs.