GUID Generator

Supported Formatting Options

Format	Example
None	xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Hyphens (-)	xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
Braces ({})	{xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}
Uppercase (ABC)	XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX
Quotes (")	"xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
Commas (,)	xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx, xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
URN (urn:uuid:)	urn:uuid:xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
Combination (Hyphens | Braces | Quotes | Commas)	{"xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"}, {"xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"}

What Is a GUID?

A GUID (Globally Unique Identifier) is a 128-bit value written as 32 hexadecimal digits, conventionally grouped as 8-4-4-4-12 and separated by hyphens. UUID (Universally Unique Identifier) is the same thing under a different name — Microsoft popularized "GUID", the IETF standard says "UUID", and in practice the terms are interchangeable.

The point of a GUID is that you can generate one anywhere, at any time, without asking a central authority whether it is taken. Two developers on opposite sides of the world, both offline, can each create identifiers and the values will not collide. That property is what makes GUIDs so useful in distributed systems, where a shared auto-incrementing counter would be a bottleneck or a single point of failure.

How Unique Is "Unique"?

GUIDs are not guaranteed unique in a mathematical sense — they are drawn from a space so large that collisions are not a practical concern. A version 4 UUID has 122 random bits, which is about 5.3 × 10³⁶ possible values.

To put that in perspective: you would need to generate roughly 2.6 × 10¹⁸ GUIDs before the chance of a single collision reached 50%. At a billion GUIDs per second, that would take about 85 years. For any realistic application, treating them as unique is entirely safe.

Version 4 and Where the Randomness Comes From

This tool produces version 4 UUIDs — the random variety, and by far the most commonly used. Other versions exist: version 1 embeds a timestamp and the machine's MAC address, version 5 derives a value deterministically from a name, and version 7 (newer) is time-ordered so identifiers sort chronologically. Version 4 is the right default when you simply need an identifier with no structure and no leaked information.

Randomness comes from your browser's cryptographically secure generator, not a general-purpose one. This matters more than it sounds: a predictable generator would let someone guess identifiers they were never given, which is a genuine security problem if a GUID acts as an unguessable URL for a shared document or a password reset.

Formatting Options

The same 128-bit value gets written differently across ecosystems, which is why the options above exist:

• Hyphens — the standard 8-4-4-4-12 grouping. Removing them gives a compact 32 character string, common in URLs and database columns.
• Braces — the registry and COM convention on Windows, and what .NET produces with the "B" format specifier.
• Uppercase — the standard says lowercase, but plenty of Microsoft tooling emits uppercase and some systems compare case-sensitively.
• Quotes and commas — generate a list you can paste straight into an array literal, a CSV column, or a SQL IN clause.
• URN prefix — the urn:uuid: form defined by RFC 4122, used where a UUID must be expressed as a formal URI.

Common Uses

• Database primary keys — lets clients create records offline and sync later, and avoids exposing row counts the way sequential IDs do.
• Distributed systems — every service can mint identifiers independently with no coordination.
• Idempotency keys — attach one to a payment or API request so a retry cannot be processed twice.
• Correlation IDs — tag a request at the edge and trace it across every service and log line it touches.
• File and object names — avoid collisions in shared storage without coordinating names.
• Test fixtures — generate throwaway identifiers that will not clash with real data.

Trade-offs Worth Knowing

GUIDs are not free. At 16 bytes they are four times the size of a 32-bit integer, and as text they occupy 36 characters. In a database, random keys scatter inserts across the index rather than appending to the end, which can hurt write performance and cache locality on large tables. They are also awkward for people — nobody reads a GUID over the phone.

Where those costs matter, common approaches are a sequential primary key paired with a GUID as the externally visible identifier, or a time-ordered UUID variant that preserves insert locality.

Frequently Asked Questions

Are GUID and UUID the same thing?

In practice, yes. Both describe a 128-bit identifier in the same format. "GUID" comes from Microsoft's terminology and "UUID" from the IETF specification, but a value produced by either name is interoperable.

Can two GUIDs ever be identical?

It is theoretically possible and practically irrelevant. With 122 random bits, you would need to generate quintillions of values before a collision became likely. A faulty random number generator is a far more realistic risk than the mathematics, which is why this tool uses your browser's cryptographic generator.

Is a GUID secret?

Treat it as unguessable, not as a secret. A version 4 GUID is unpredictable enough to serve as an unlisted URL, but it may still be logged, cached by proxies, stored in browser history, or leaked in a referrer header. For actual authentication, use a real credential.

Does removing the hyphens change the value?

No. The hyphens are purely presentational. The same 128 bits with or without them represent the same identifier — though a system storing it as a string will treat the two spellings as different text, so be consistent.

Are these generated on a server?

No. Generation happens entirely in your browser, so the identifiers are never transmitted or recorded anywhere. Disconnect from the internet and the tool keeps working.