Generate UUIDs (Universally Unique Identifiers) in bulk. Supports UUID v4. Copy all or individually.
The UUID / GUID Generator produces cryptographically random version 4 UUIDs in bulk using the browser's native crypto.randomUUID API, with output format options including lowercase, uppercase, no-hyphens, and brace-wrapped styles. It is the fastest way for developers, database administrators, and QA testers to create unique identifiers for records, sessions, test fixtures, or distributed system entities without installing any software. Generate up to 500 UUIDs at a time and download them as a text file.
A UUID (Universally Unique Identifier), also called a GUID (Globally Unique Identifier), is a 128-bit identifier formatted as 32 hexadecimal digits in the pattern xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. Version 4 UUIDs are randomly generated - all bits except a few version/variant markers are set using a cryptographically secure random source. The probability of two randomly generated UUID v4s colliding is astronomically small, making them safe to use as unique identifiers without a central registry or coordination.
Use the generator above - set your desired count (1-500), choose a format (lowercase, uppercase, no hyphens, or brace-wrapped), and click Generate. All UUIDs are produced using the browser's crypto.randomUUID() API, which provides cryptographically random values. You can copy all UUIDs to the clipboard or download them as a text file. No sign-up or registration is required.
UUID and GUID refer to the same concept - a 128-bit unique identifier. "UUID" is the open standard term from RFC 4122, while "GUID" (Globally Unique Identifier) is Microsoft's name for the same format used in COM, .NET, and Windows systems. In practice they are interchangeable - a UUID v4 generated here is a valid GUID. The only cosmetic difference is that GUIDs are sometimes wrapped in curly braces: {xxxxxxxx-xxxx-...}, which this generator supports via the "With braces" format option.
UUID primary keys are excellent for distributed systems where you need to generate IDs client-side or across multiple servers without coordination - they guarantee global uniqueness without a central sequence. The trade-off is that UUID v4 primary keys are random, which causes index fragmentation in B-tree indexes (e.g., PostgreSQL, MySQL InnoDB) and can slow insert performance at very high scale. For high-write single-server workloads, a sequential UUID variant (UUID v7) or a BIGSERIAL integer key may be more performant. For most applications, UUID v4 keys work perfectly well.
In modern JavaScript: crypto.randomUUID() (available in all modern browsers and Node.js 14.17+). In Python: import uuid; str(uuid.uuid4()). In PHP: bin2hex(random_bytes(16)) with formatting, or use the ramsey/uuid package for a standards-compliant UUID v4. In C#/.NET: Guid.NewGuid().ToString(). Each of these uses a cryptographically secure random number generator, equivalent to the UUIDs produced by this online generator.