Numbers

GUID Generator

A GUID generator gives you instant access to one or more Globally Unique Identifiers — Microsoft's implementation of the 128-bit UUID standard used to uniquely identify objects across systems without central coordination. Whether you're seeding a database, writing C# code, or configuring a Windows Registry entry, the right format matters: braced GUIDs for .NET, hyphenless strings for compact storage, uppercase for legacy COM interfaces. This tool lets you generate up to hundreds at once, so you can paste a whole batch directly into your code or test data without stopping your workflow. GUIDs are built on the UUID v4 specification, meaning the uniqueness comes from randomness rather than a timestamp or hardware address. That makes them safe to generate client-side, share publicly, and store in distributed databases without risking collisions across servers. The probability of two randomly generated GUIDs matching is roughly 1 in 5.3 undecillion — for practical purposes, treat them as globally unique. The format you choose has real consequences in your stack. SQL Server and Entity Framework often expect braced or hyphenated lowercase GUIDs. Oracle and MySQL handle stripped hex strings more cleanly. Windows COM interfaces traditionally used uppercase. Picking the wrong format can cause silent type-mismatch bugs, so match your output format to the consuming system from the start. This generator handles the formatting and bulk generation for you, so you can focus on the code that uses the GUIDs rather than writing a script just to produce them. Set your count, choose your format, and copy the results straight into your editor or test fixture.

How to Use

  1. Set the count field to the number of GUIDs you need, from 1 up to your desired batch size.
  2. Choose a format from the dropdown: lowercase, uppercase, braced for .NET, or no-hyphens for compact storage.
  3. Click Generate to produce the full list of GUIDs instantly.
  4. Click Copy or select all output text, then paste directly into your code, SQL script, or test fixture.

Use Cases

  • •Seeding primary key columns in SQL Server or PostgreSQL migrations
  • •Generating test GUIDs for unit tests and mock API responses
  • •Creating unique identifiers for Windows Registry configuration entries
  • •Populating GUID fields in .NET Entity Framework model scaffolding
  • •Building bulk test datasets for QA pipelines needing unique row IDs
  • •Creating correlation IDs for distributed service request tracing
  • •Assigning unique asset IDs to game objects in Unity or Unreal
  • •Generating client IDs for OAuth app registrations or API key placeholders

Tips

  • →Use braced format when pasting into Visual Studio project files — the IDE expects the curly-brace wrapper by default.
  • →Generate 20–30 at once when writing unit tests; having extras on hand avoids re-running the tool mid-session.
  • →For PostgreSQL UUID columns, lowercase hyphenated format matches the output of gen_random_uuid() and avoids conversion overhead.
  • →Paste no-hyphens GUIDs into Elasticsearch or DynamoDB document IDs where hyphens in the key string can confuse query parsers.
  • →If you need GUIDs that sort chronologically, this tool's random output won't help — use a UUIDv7 generator or NEWSEQUENTIALID() in SQL Server instead.
  • →When storing GUIDs in MySQL, use BINARY(16) and strip the hyphens — the varchar approach wastes 20 bytes per row at scale.

FAQ

What is the difference between a GUID and a UUID?

They are the same thing. UUID is the open standard (RFC 4122); GUID is Microsoft's name for the same 128-bit identifier. Both share the same format, collision probability, and structure. You'll see GUID in Windows, COM, and .NET documentation, and UUID everywhere else — but they're interchangeable in practice.

What does the braced GUID format look like and when do I use it?

Braced format wraps the GUID in curly braces: {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}. Use it when working with .NET's Guid.Parse() method, Windows Registry keys, COM component registration, or Visual Studio project files (.csproj, .sln). Many .NET APIs will reject an unbraced string where a braced one is expected.

Are GUIDs safe to use as database primary keys?

Yes, with a caveat. Random GUIDs as clustered primary keys in SQL Server cause page fragmentation because new rows insert randomly into the index rather than at the end. Use NEWSEQUENTIALID() in SQL Server or UUIDv7 if you need GUID primary keys with append-friendly ordering. For non-clustered indexes or other databases like PostgreSQL, random GUIDs work fine.

Should I use uppercase or lowercase GUIDs?

GUIDs are case-insensitive, so both work functionally. Use lowercase for modern APIs, JSON payloads, and cross-platform compatibility. Use uppercase when working with legacy COM interfaces, older Windows APIs, or codebases that already use uppercase consistently. Mixing cases within one system is fine technically but hurts readability in logs and diffs.

What is the no-hyphens GUID format used for?

Stripping hyphens produces a compact 32-character hex string. This is useful for URL slugs, compact database storage where the hyphens waste bytes, certain NoSQL document IDs, and file naming where hyphens conflict with tooling. Always document that the field is a stripped GUID so future developers know it's not an arbitrary hex hash.

How many GUIDs can I safely generate at once?

This generator lets you set the count field to produce a batch in one click. For most workflows, 10–50 is enough for seeding test data or placeholder IDs. If you need thousands, generate multiple batches or write a script using your language's built-in UUID library — most modern runtimes (Python, Node.js, .NET, Java) have one built in.

Can two generated GUIDs ever be the same?

In theory yes, in practice essentially never. UUID v4 has 122 random bits, giving roughly 5.3 × 10^36 possible values. You would need to generate approximately 2.7 quintillion GUIDs before a 50% chance of a single collision appears. For any realistic application — even large-scale distributed systems — treat randomly generated GUIDs as guaranteed unique.

Are GUIDs generated here safe to use in production?

For identifiers, yes. The GUIDs are randomly generated in your browser using the Web Crypto API, which produces cryptographically random values. Do not use a GUID as a secret, password, or security token — they are identifiers, not credentials. A GUID visible in a URL or log is not a security risk, but it was never designed to be unguessable.