UUID Generator
Generate and validate UUIDs (v1, v4)
UUID Versions
Random UUID using secure random numbers
Time-based UUID using timestamp and MAC address
Time-ordered, sortable identifier with a millisecond timestamp prefix — ideal as a database key.
Deterministic: the same namespace and name always produce the same UUID, using SHA-1 hashing.
The special all-zero UUID (00000000-0000-0000-0000-000000000000) used as a placeholder.
What is UUID Generator?
The UUID Generator is a free online tool that creates universally unique identifiers and validates existing ones. A UUID is a 128-bit value, written as 36 characters including hyphens, that is designed to be unique across space and time without any central authority. This tool supports five flavours: random version 4, time-based version 1, time-ordered sortable version 7, deterministic namespace-based version 5 (SHA-1), and the all-zero NIL UUID. You can produce a single identifier or a batch of up to one hundred at once, and control the output format with letter case, optional hyphens, curly braces, or a urn:uuid: prefix. A built-in validator checks whether any string is a properly formatted UUID and reports its version. Generation happens entirely in your browser using the secure crypto API, so no identifiers are ever sent to a server.
How to use UUID Generator?
Generating and validating UUIDs takes only a moment and happens entirely in your browser:
- 1 Pick a version. Choose v4 for random IDs, v1 or v7 for time-based ones, v5 for a deterministic namespace ID, or NIL for the all-zero placeholder. For v5, also select a namespace (DNS, URL, OID, X.500, or a custom UUID) and type a name to hash.
- 2 Choose how many you need. Enter any quantity from one to one hundred to mint a single identifier or a whole batch for seeding databases and test data.
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3
Set the formatting. Switch between lowercase and uppercase, toggle hyphens off for a compact 32-character form, or wrap the result in braces or a
urn:uuid:prefix. - 4 Click Generate to create the identifiers instantly, then copy a single value, use Copy All, or download the batch. You can also paste any UUID into the validator to confirm its format and version.
Why use this tool?
UUIDs solve a deceptively hard problem: generating identifiers that are guaranteed to be unique without coordinating with a central server. This makes them perfect for distributed systems, where multiple machines must create records without colliding. Developers use them for database primary keys, session tokens, file names, message IDs, and idempotency keys. Version 4 relies on secure random generation, making accidental collisions virtually impossible, while version 7 keeps that randomness but prefixes a millisecond timestamp so the IDs sort in creation order — a big win as a database key. Version 5 is deterministic, turning a namespace and a name into a stable, repeatable ID. Being able to mint a batch instantly, choose the exact output format, or validate an existing identifier saves real time during development and testing. Because everything runs locally in your browser with secure randomness and no signup, the tool is fast, private, and always available.
Examples
Generate version 7 UUIDs so new rows naturally sort in insertion order, giving you the uniqueness of a UUID with the locality of a sequential key.
Pick the URL namespace and enter a domain to produce the same UUID every time — handy for stable identifiers derived from existing data.
Generate a batch of up to one hundred version 4 UUIDs at once and copy them all to populate primary keys in test records without any risk of duplicates.
Paste a string into the validator to confirm it is a properly formatted UUID, even when wrapped in braces or a urn:uuid: prefix, before storing it.
Frequently Asked Questions
Is the UUID Generator free to use?
Yes. The tool is completely free, with no signup, no limits, and no account required. You can generate and validate as many UUIDs as you like.
Are the generated UUIDs sent to a server?
No. All generation happens entirely in your browser using the secure crypto API, so the identifiers are never transmitted or stored anywhere.
What is the difference between v1, v4, and v7?
Version 1 is time-based from a timestamp and node ID, version 4 is fully random, and version 7 combines a millisecond timestamp with random bits so the IDs are both unique and sortable in creation order.
What is a version 5 (namespace) UUID?
Version 5 is deterministic: it hashes a namespace UUID together with a name using SHA-1, so the same namespace and name always produce the exact same UUID. It is generated locally with the browser crypto API.
What is the NIL UUID?
The NIL UUID is the special all-zero value 00000000-0000-0000-0000-000000000000, used as a placeholder or default when no real identifier is available.
What output formats are supported?
You can switch between lowercase and uppercase, remove the hyphens for a 32-character form, wrap the value in curly braces, or add a urn:uuid: prefix — and generate up to one hundred at once.
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