Is GUID the same as UUID?

Practically yes. GUID (Globally Unique Identifier) is Microsoft terminology. UUID (Universally Unique Identifier) is the IETF standard term (RFC 4122). The format, generation algorithms, and uniqueness guarantees are identical.

Why are there two names?

Microsoft coined GUID before the UUID standard was formalized. When IETF published RFC 4122, they used UUID. Microsoft continued using GUID in Windows, .NET, and SQL Server. The rest of the industry adopted UUID.

Which term should I use?

Use UUID in most contexts. Use GUID when working specifically with Microsoft technologies (.NET, SQL Server, Azure) where the documentation and APIs use that term. They refer to the same thing.

Is the format exactly the same?

Yes. Both use 32 hex characters in 8-4-4-4-12 grouping with hyphens. Microsoft sometimes wraps GUIDs in curly braces like {550e8400-e29b-41d4-a716-446655440000} but that is just display preference, not a format difference.

Can I use a UUID where a GUID is expected?

Yes. A v4 UUID generated by any tool is a valid GUID for Microsoft systems. The bytes and format are interchangeable.

Home / Blog / Generator Tools

GUID vs UUID — What Is the Difference? (Spoiler: Almost Nothing)

Last updated: April 20265 min readGenerator Tools

GUID and UUID are the same thing. Different name, same format, same randomness, same uniqueness. GUID is Microsoft's term. UUID is everyone else's term. That is the entire difference.

The Naming Split

	GUID	UUID
Full name	Globally Unique Identifier	Universally Unique Identifier
Standard	Microsoft COM/OLE (1990s)	RFC 4122 (IETF, 2005)
Used by	Windows, .NET, SQL Server, Azure	Linux, macOS, PostgreSQL, most languages
Format	8-4-4-4-12 hex	8-4-4-4-12 hex
Size	128 bits	128 bits
Versions	Same (v1-v5)	Same (v1-v5, plus v6-v7 draft)

The One Visual Difference

Microsoft often displays GUIDs with curly braces:

GUID style: {550e8400-e29b-41d4-a716-446655440000}
UUID style: 550e8400-e29b-41d4-a716-446655440000

The braces are just decoration. The actual identifier is identical.

Which Term to Use

Writing .NET code? Say GUID. The class is System.Guid.
Writing SQL Server queries? Say GUID. The type is uniqueidentifier.
Writing Python, Java, Go, Rust, or JavaScript? Say UUID.
Writing PostgreSQL? Say UUID. The type is uuid.
Writing documentation? Say UUID unless your audience is exclusively Microsoft developers.

Generating Both

Our UUID Generator produces v4 random identifiers. These are valid as both UUIDs and GUIDs. Paste one into a .NET Guid.Parse() call and it works. Paste one into PostgreSQL's uuid column and it works. Same bits, different name.

Generate a UUID (or GUID, if you prefer). Same thing.

Generate Now →

Related: Hash Generator for SHA-256/SHA-1/SHA-512, Base64 Encoder for encoding IDs.

GUID vs UUID — What Is the Difference? (Spoiler: Almost Nothing)

The Naming Split

The One Visual Difference

Which Term to Use

Generating Both

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