In most day-to-day development, UUID and GUID refer to the same 128-bit identifier format. The difference is mostly vocabulary, with a few ecosystem details that matter when bytes move between systems.
Key takeaways
- UUID is the standards-oriented term.
- GUID is common in Microsoft tooling.
- The text format is usually compatible across platforms.
The short answer
UUID means universally unique identifier. GUID means globally unique identifier. Most developers use the words for the same kind of value: a 128-bit identifier displayed in hexadecimal groups.
If a .NET API asks for a GUID and a web API sends a UUID string, the text value is usually accepted as long as the format is valid.
Why there are two names
The UUID name is common in standards, Linux tooling, databases, web frameworks and distributed systems. GUID became the everyday term in Microsoft ecosystems such as Windows, COM, .NET and SQL Server.
Teams that work across both worlds often keep the database type as UUID or uniqueidentifier, then use whichever name fits the language layer.
Where compatibility can surprise you
The string form is the easy part. The subtle issue is binary representation. Some Microsoft APIs historically display or store parts of a GUID with different byte ordering internally. That does not usually matter if you pass the hyphenated string, but it can matter if you serialize raw bytes.
When systems disagree, compare the canonical text value first. It is less ambiguous than a byte array copied from one runtime into another.
UUID/GUID text shape:
123e4567-e89b-12d3-a456-426614174000Which word should your product use
Use GUID if your audience is mostly .NET, Windows or SQL Server developers. Use UUID if your audience is broader or standards-focused. If your docs serve both groups, introduce both once and then stay consistent.
The site includes a dedicated GUID generator page because many people search that exact phrase, but the generated values follow the same familiar UUID text shape.