What is a UUID generator?

A UUID generator is a tool that creates Universally Unique Identifiers — 128-bit values designed to be unique across space and time without a central authority. UUIDs are used as database primary keys, API resource IDs, session tokens, and file names. This generator supports versions 1 (time-based), 4 (random), and 7 (Unix-epoch time-based), and runs entirely in your browser.

Can you decode a UUID?

Yes. Paste any UUID or GUID into the parse panel on this page to see its normalized form, version number, variant, and — for time-based versions (v1, v6, v7) — the embedded timestamp. The parser accepts braces, parentheses, no-hyphen, and mixed-case formats.

UUID stands for Universally Unique Identifier. It is a 128-bit number, usually written as 32 hexadecimal digits in five groups separated by hyphens (8-4-4-4-12). UUIDs are defined by RFC 9562 (formerly RFC 4122) and are designed so that the probability of generating a duplicate without coordination is negligible.

What is UUID used for?

UUIDs are used wherever you need a unique ID without a central allocator: database primary keys, distributed system entity IDs, API resource identifiers, session and correlation IDs, file and object storage keys, and message queue identifiers. Version 4 (random) is the most common general-purpose choice; version 7 is growing in popularity for sortable database keys.

Is 00000000-0000-0000-0000-000000000000 a valid UUID?

Yes. The all-zeros value is called the nil UUID (or empty GUID in .NET). It is a valid, well-defined special value in RFC 9562, commonly used as a sentinel meaning 'no ID assigned' or 'not set'. In .NET it is Guid.Empty. This tool includes a one-click nil UUID preset.

How can I convert a UUID to a string?

A UUID is already a string when displayed. The standard canonical form is lowercase hex with hyphens (e.g. 550e8400-e29b-41d4-a716-446655440000). .NET GUIDs support additional string formats: D (hyphens), N (no hyphens), B (braces), P (parentheses), and X (hex struct initializer). Use the format toggles on this generator to output any of these forms.

What's the difference between a UUID and a GUID?

There is no structural difference. GUID (Globally Unique Identifier) is Microsoft's name for the same 128-bit value defined by RFC 4122/9562. A GUID and a UUID with the same bytes are identical. The term GUID is common in Windows and .NET ecosystems; UUID is the IETF/RFC term used everywhere else.

Which UUID version should I use?

Use v4 for general-purpose random IDs (most common). Use v7 if you want database-sortable keys with an embedded Unix timestamp. Use v1 only for legacy compatibility with systems that expect time-based UUIDs. Avoid v1/v7 when you need unpredictability — they embed timestamps that can leak creation time.

Are these UUIDs cryptographically secure?

Version 4 UUIDs generated here use crypto.getRandomValues() (or crypto.randomUUID()), which is cryptographically secure in modern browsers. Version 1 and v7 embed timestamps and are not designed for secrecy — do not use them as unguessable tokens. For security-sensitive tokens, use v4 or a dedicated CSPRNG.

Is this free, and do you store the UUIDs I generate?

Yes, it is completely free. Every UUID and GUID is generated and parsed entirely in your browser — nothing is sent to a server or stored by DesignRevision. No signup required.

UUID & GUID Generator

Free online UUID generator — create v1, v4, or v7 UUIDs and GUIDs in bulk, any format, then decode an existing UUID.

Generate random UUIDs (v4), time-based UUIDs (v1), or sortable UUID v7 keys — up to 1,000 at once. Output in standard or .NET GUID formats (braces, no hyphens, uppercase). Paste any UUID to parse its version, variant, and timestamp. Runs entirely in your browser — no signup, no server.

UUID version

v4 is the default for general use. v7 for sortable DB keys.

Quantity

1–1,000 UUIDs per batch.

GUID format

D=standard, N=no hyphens, B=braces, P=parens, X=C struct.

Case

Special values

Click Generate to create UUIDs.

Parse a UUID or GUID

Paste any UUID or GUID — with or without hyphens, braces, or parentheses — to see its normalized form, version, variant, and embedded timestamp.

Normalized
Version
Variant
Special
Timestamp

UUID vs GUID: what's the difference?

There is no structural difference between a UUID and a GUID. Both are 128-bit identifiers defined by the same RFC standards (RFC 9562, formerly RFC 4122). GUID (Globally Unique Identifier) is the name Microsoft uses in Windows and .NET; UUID (Universally Unique Identifier) is the IETF term used in databases, Linux, and most open-source ecosystems.

A Guid.NewGuid() in C# produces the same byte layout as a v4 UUID from crypto.randomUUID() in JavaScript. The only difference is naming and string formatting conventions — .NET supports five GUID string formats (D, N, B, P, X) that this tool can output.

UUID versions explained

RFC 9562 defines eight UUID versions. This tool generates v1, v4, and v7; the parse panel recognizes all versions including v3, v5, and v6.

Version	Name	Generated here?	Use case
v1	Time-based	Yes	Legacy systems, MAC-derived node ID
v2	DCE security	No	POSIX UID/GID (rarely used)
v3	Name-based (MD5)	Parse only	Deterministic ID from namespace + name
v4	Random	Yes (default)	General-purpose unique IDs
v5	Name-based (SHA-1)	Parse only	Deterministic ID, preferred over v3
v6	Reordered time-based	Parse only	v1 with better DB index locality
v7	Unix epoch time	Yes	Sortable database primary keys
v8	Custom	Parse only	Vendor-specific experimental layouts

What's a nil UUID / empty GUID?

The nil UUID is the all-zeros value 00000000-0000-0000-0000-000000000000. It is a valid, well-defined special value in RFC 9562 — not an error or invalid ID. In .NET it is called Guid.Empty and is commonly used as a sentinel meaning "no ID assigned yet" or "not set".

The opposite extreme is the max UUID ffffffff-ffff-ffff-ffff-ffffffffffff, defined in RFC 9562 as the largest possible UUID value. Both are available as one-click presets in the generator above.

Generate a UUID in code

Every major language has a built-in UUID/GUID generator. Version 4 (random) is the default in all of them:

Language	Generate v4 UUID
JavaScript	crypto.randomUUID()
Python	import uuid; uuid.uuid4()
Java	UUID.randomUUID()
C# / .NET	Guid.NewGuid()

Code Snippets

Frequently asked questions

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