GUID Generator

Generate Global Unique Identifiers (GUIDs) instantly and for free with our GUID Generator, which supports RFC 4122 compliant GUIDs. Supports standard, registry and COMB formats. Pre-includes UUID & GUID conversion. No signups, no tracking, no limits: your GUIDs are generated in your browser, all for privacy.

Standard GUID Format — The most common format used in .NET, Windows APIs, and most programming languages. Format: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
Standard
Registry GUID Format — Common in Windows Registry Editor, some .NET methods, and configuration files. Format: {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}
Registry
COMB GUID Format — Sequential GUID with embedded timestamp for optimal database index performance. Recommended when using GUIDs as primary keys in SQL Server or similar databases. Format: xxxxxxxx-xxxx-7xxx-Nxxx-xxxxxxxxxxxx
COMB
Format Options

Preview:

xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
UUID ↔ GUID Converter

Instantly convert between UUID and GUID formats. Works with or without hyphens.

Supports: with/without hyphens, with/without curly braces
Bulk Generation
Max: 100 per batch
Recent History

No GUIDs generated yet. Your recent GUIDs will appear here.

    What is a GUID Generator?

    A GUID Generator is a free online service that generates Globally Unique Identifiers (GUID) which are 128-bit labels that are used in computing to uniquely identify information without relying on a central authority. The term GUID is Microsoft’s version of the internationally accepted UUID (Universally Unique Identifier) standard that was specified in RFC 4122.

    This GUID Generator creates GUIDs in different formats: standard hyphenated format (most programming languages), curly brace format (Windows configuration) and COMB format (optimized for database performance).

    It is called a GUID or UUID, but they are almost impossible to collide. Even 1 billion GUIDs a second is not enough: For that many, you would probably have to wait more than 100 billion years before you’d find one duplicate.

    Guid vs UUID: What is the difference?

    In real life, GUID and UUID are exactly the same, they are both 128-bit identifiers. There is only a difference in the terminology:

    • UUID – Universally Unique Identifier (RFC 4122) is the internationally accepted term for this.
    • GUID, a Microsoft naming system, is mainly used in Windows and .NET environments

    In Windows documents, “GUID” refers to what?NET code” is another term for SQL Server, which is essentially the same identifier format as “UUID. Our GUID Generator generates UUIDs which are compliant with the RFC 4122 standard, which can be used anywhere UUIDs are required.

    Understanding COMB GUIDs

    A popular problem is random GUIDs leading to index fragmentation in databases, and COMB GUIDs were developed to address that issue. COMB GUIDs will preserve time-ordering, but they will still be unique due to a 48-bit field that contains the time.

    COMB is an acronym for GUID plus creation time (from Jimmy Nilsson’s original implementation). The final string is a typical GUID but is sortable, thus suitable for database primary keys.

    Some of the main advantages of COMB GUIDs:

    • Improved performance for B-tree indexes in SQL Server and other databases
    • Fewer Page Splits and Index Fragmentation.
    • Newer inserts go to the end of the index (append-only behavior)
    • Unique, with embedded timestamp for debugging, still globally unique.
    • When you need GUIDs as database keys, and you want optimum write performance, use our GUID Generator with COMB format.

    GUID Format Comparison

    Compare the three GUID formats available in this generator:

    FormatExampleBest Use CaseDatabase Performance
    Standard550e8400-e29b-41d4-a716-446655440000General purpose, APIs, config filesModerate (random)
    Registry{550e8400-e29b-41d4-a716-446655440000}Windows Registry, .NET Guid.ToString(“B”)Moderate (random)
    COMB018a1c00-0000-7xxx-9xxx-xxxxxxxxxxxxDatabase primary keys, sequential needsExcellent (sequential)

    FAQs

    What is GUID and how does a GUID Generator work?

    A GUID is a 32-character hexadecimal identifier, 128 bits long, that is globally unique. This GUID Generator generates cryptographically secure random or sequential identifiers in your browser, via the JavaScript crypto API. The resulting identifiers are RFC 4122 compliant and will work everywhere UUIDs are expected.

    What’s the difference between GUID and UUID?

    GUID and UUID are identical identifiers by a different name; both are 128-bit ID standards. UUID is the universally accepted identifier (RFC 4122) and GUID is the naming convention used by Microsoft in Windows.NET, and SQL Server. Both are the same data structures and can be used in place of each other. Our GUID Generator generates identifiers which meet both conventions.

    What is a COMB GUID and why would I need it?

    Comb GUID is a sequential identifier with random data added to it. The name “COMB” was derived from “Combined” which combines the creation time with a GUID. Use COMB GUIDs where you require GUIDs as database primary keys and performance of the generated indexes is important. The standard random GUIDs create page splits and fragmentation in the B-tree indexes, and COMB GUIDs add at the end as would auto-increment integers, but keep the distributed uniqueness advantage of GUIDs.

    How to use UUID vs GUID?

    Note: UUID and GUID are interchangeable terms, and converting the GUID to a UUID involves simply changing the format (adding or removing hyphens and curly braces). We have a UUID↔GUID Converter built-in to convert between the two. You can also use .NET’s Guid.The various ToString() format specifiers: “D” for standard (hyphens), “N” for no hyphens, “B” for curly braces and Parse()

    What GUID formats does .NET support?

    The Guid struct has four possible formats when using the ToString: D (the default format, 38 characters separated by hyphens), N (32 hex digits, no hyphens), B (curly braces like in a registry) and P (parentheses). Our GUID Generator generates at standard and registry formats directly. These format specifiers can be used to convert the output in other formats.

    Can GUIDs be used safely in security sensitive applications?

    Modern browsers generate standard GUIDs with cryptographically secure random number generation (CSPRNG), which makes it impossible to predict them by brute force. GUIDs are not suitable, however, for cryptographic use, high security applications or any application that requires provable randomness. In security sensitive applications, use dedicated security primitives such as Web Crypto API or security token specific libraries.

    Can I use GUIDs as database primary keys?

    Yes, GUIDs are good and fit the bill of a primary key, and they have the added benefit of generating them distributed without the need for coordination between transactions. But normal random GUIDs lead to index fragmentation in some databases. COMB GUIDs give sequential ordering, and still are unique, for best performance. SQL Server has NEWSEQUENTIALID(), and COMB GUIDs come with the same advantages, and can be distributed.

    Is this GUID Generator free or paid?

    Absolutely! No signup or installation is required with this GUID Generator. Everything is generated client-side, in your browser, via JavaScript, so that means that no generated GUIDs ever leave your device. You can even use it even as soon as you load the initial page, offline. Create as many GUIDs as you want – it’s a whole lot of GUIDs!

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