UUID Generator
Generate cryptographically random UUID v4 identifiers. Create single or bulk UUIDs for databases, APIs, session tokens, and distributed systems. RFC 4122 compliant.
UUID Generator — Generate Unique UUIDs v4 Online Free: Free UUID Generator tool: generate random UUID v4 identifiers instantly. Create single or bulk UUIDs with uppercase, lowercase, and no-dash options. Copy.
How to Generate UUIDs
Generate Single UUID
Click "Generate New" to create a single UUID v4. The result appears in the input field — click the copy button to clipboard.
Bulk Generate
Set the count (up to 1000), choose formatting options (uppercase, no dashes), and click "Generate Bulk" to create multiple UUIDs at once.
Copy or Download
Copy all UUIDs to your clipboard or download as a text file. Each UUID is on its own line, ready for database seeding or configuration files.
What Is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit value used to uniquely identify information in computer
systems. Also known as a GUID (Globally Unique Identifier) in Microsoft ecosystems, UUIDs are formatted as
32 hexadecimal digits displayed in five groups separated by hyphens: 8-4-4-4-12 (e.g.,
550e8400-e29b-41d4-a716-446655440000). The standard is defined in RFC 4122 and has become the
de facto standard for generating unique identifiers without coordination between systems.
UUID version 4 (v4), which this tool generates, uses random or pseudo-random numbers. Of the 128 bits, 6 are fixed (4 bits for the version number "0100" and 2 bits for the variant "10"), leaving 122 bits of randomness. This produces 5.3×10³⁶ possible UUIDs — so many that generating 1 billion UUIDs per second for 85 years would produce a 50% probability of a single collision. In practice, collisions are essentially impossible.
Our generator uses crypto.getRandomValues(), the Web Crypto API's cryptographically secure
random number generator. Unlike Math.random(), which uses a predictable algorithm, the crypto
API draws from your operating system's entropy pool (mouse movements, hardware noise, timing variations).
This makes the generated UUIDs suitable for security-sensitive applications like session tokens, API keys,
and database primary keys.
UUIDs solve a fundamental problem in distributed systems: how do you generate unique identifiers without a central authority? Traditional auto-increment IDs require a database to coordinate numbers. UUIDs let any server, client, or device generate an identifier independently with near-zero collision risk. This is essential for microservices architectures, offline-first applications, and systems that sync data between multiple databases.
Why Use Our UUID Generator?
Cryptographically Secure
Uses the Web Crypto API (crypto.getRandomValues) for true randomness. Suitable for session tokens, API keys, and security-sensitive identifiers.
Bulk Generation
Generate up to 1000 UUIDs at once. Perfect for database seeding, test data, migration scripts, and configuration files.
Format Options
Standard lowercase with dashes, uppercase for .NET/SQL Server conventions, or no-dash format for compact storage and URL-safe identifiers.
Copy & Download
One-click copy to clipboard or download as a .txt file. Each UUID on its own line, ready for immediate use in code or configuration.
Frequently Asked Questions
Theoretically, yes — but the probability is astronomically low. With 122 random bits, there are 5.3×10³⁶ possible v4 UUIDs. You'd need to generate approximately 2.7×10¹⁸ (2.7 quintillion) UUIDs to have a 50% chance of a single collision. For all practical purposes, UUID v4 collisions don't happen.
They're the same thing. UUID is the standard term used in RFC 4122 and most programming languages. GUID (Globally Unique Identifier) is Microsoft's term, used in .NET, SQL Server, and Windows APIs. The format, generation algorithm, and collision properties are identical.
UUIDs work well as primary keys in distributed systems, but have tradeoffs. Advantages: no coordination needed, safe for replication, doesn't reveal record count. Disadvantages: larger storage (16 bytes vs 4-8 for integers), random UUIDs cause index fragmentation in B-tree databases, and they're harder to read in debugging. Consider UUID v7 (time-sorted) for better index performance.
V1: timestamp + MAC address (reveals creation time and device). V3: MD5 hash of a name. V4: random (most common, what this tool generates). V5: SHA-1 hash of a name. V7 (new): Unix timestamp + random (time-sortable, better for databases). V4 is the most widely used because it requires no input and has no information leakage.
Yes — our generator uses crypto.getRandomValues(), which is the browser's cryptographically secure pseudo-random number generator. The output has sufficient entropy for session tokens, CSRF tokens, and similar security identifiers. However, for password hashing or encryption keys, use purpose-built cryptographic functions instead.