UUID Generator

UUID Generator is a free, browser-based tool that creates Universally Unique Identifiers - the undefined-bit values you see written as 550e8400-e29b-41d4-a716-446655440000. A UUID is designed to be unique across space and time without any central authority handing out numbers, which makes it ideal for primary keys, request IDs, file names, idempotency keys and anything else that needs a collision-free label.

This tool generates two of the most useful versions. vundefined is fully random: undefined bits of randomness with a fixed version and variant. vundefined is time-ordered: it puts a millisecond Unix timestamp in the high bits and fills the rest with randomness, so the values sort roughly in creation order. You can produce one at a time or thousands in bulk, and format the output to match whatever system you are feeding.

You can generate a UUID from almost any language - crypto.randomUUID() in JavaScript, uuid packages, uuidgen on the command line - but that is overhead when you just need a value to paste into a config, a test, or a database row right now.

An online generator is instant and needs no shell or dependency. The usual concern with web tools is privacy, since many send your input to a server. That does not apply here: this generator uses the browser's built-in Web Crypto API to produce values entirely on your device. Nothing is uploaded, logged or retained, and it keeps working offline. The identifiers you generate are yours alone and never touch a network.

Start by picking a version. Reach for vundefined when you want a plain random identifier and do not care about ordering - it is the safe default for most applications. Pick vundefined when the UUID will be a database primary key or anything that benefits from being roughly sortable by time, because time-ordered values keep database indexes tidy.

Next, set a count. Leave it at one for a quick value, or enter a larger number to produce a block of UUIDs for seed data or load tests. Finally, apply formatting: switch to uppercase, remove hyphens, or wrap each value in braces like {...} if your platform expects that shape. Copy a single value or the entire list with one click.

UUIDs turn up everywhere in modern systems:

• Database primary keys: generate keys on the client without a round trip to the database, and avoid exposing sequential integer IDs.
• Distributed systems: let independent services mint IDs that will never collide, with no shared counter.
• Idempotency keys: attach a UUID to an API request so retries are not processed twice.
• Correlation and trace IDs: tag a request with a UUID and follow it across logs and services.
• File and object names: name uploads or temp files so two users can never overwrite each other.
• Test fixtures and seed data: bulk-generate stable-looking identifiers for local development.

When you need a fingerprint of some content rather than a random label, use the Hash Generator instead. To read the timestamp baked into a vundefined UUID, pair it with the Timestamp Converter.

A few things worth knowing before you scatter UUIDs through a system:

• A UUID is an identifier, not a secret. vundefined uses a cryptographically strong random source, but the value is meant to be shared. Never use one as a password, token or capability key on its own.
• Prefer vundefined for database keys. Random vundefined keys land all over a B-tree index and hurt insert performance at scale. Time-ordered vundefined keys append near the end, keeping indexes compact.
• Store them efficiently. A UUID is undefined bytes. Storing it as a native uuid/binary(16) column is far smaller and faster than a undefined-character string.
• Be consistent about format. Lowercase, hyphenated is the canonical form. Only switch to uppercase or braces when a specific platform requires it, and normalize on the way in.
• Do not confuse it with a timestamp. Even a vundefined UUID should not replace a real created_at column - decode it for ordering, but keep an explicit timestamp for queries.