Generate random UUIDs (Universally Unique Identifiers) for databases, APIs, and applications.
The UUID Generator is a free, browser-based tool that creates random Version 4 UUIDs (Universally Unique Identifiers) instantly. Generate one UUID or hundreds at a time, choose from multiple output formats, and copy individual UUIDs or the entire batch with a single click. No installation, no account, and no server calls — everything runs locally in your browser.
A UUID (Universally Unique Identifier), also known as a GUID (Globally Unique Identifier) in Microsoft contexts, is a 128-bit number used to uniquely identify information in computer systems. The standard format is a 32-character hexadecimal string divided into five groups by hyphens: 8-4-4-4-12 characters (e.g., 550e8400-e29b-41d4-a716-446655440000). UUIDs are standardized by RFC 4122 and are widely used across virtually every programming language, database system, and platform.
Version 4 UUIDs, which this tool generates, are created using random or pseudo-random numbers. The probability of generating two identical Version 4 UUIDs is astronomically low — approximately 1 in 2^122, or about 1 in 5.3 undecillion. For all practical purposes, every UUID you generate is guaranteed to be unique, even without any central coordination or registry.
UUIDs are preferred over sequential integer IDs in many scenarios because they can be generated independently on any device or system without risk of collision. This makes them ideal for distributed systems, microservices, offline-first applications, and any situation where multiple sources need to create unique identifiers without coordinating with each other.
Choose your UUID format based on where you will use it. The standard hyphenated format (xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx) is the most widely recognized and is accepted by virtually all systems that support UUIDs. The compact format (no hyphens) is useful when you need to store the UUID in a fixed-length string field or when the hyphens would cause parsing issues. The uppercase format is sometimes required by older systems or specific APIs.
When using UUIDs as database primary keys, consider the performance implications. Random UUIDs do not sort in insertion order, which can cause index fragmentation in B-tree indexes on some databases. If insert performance is critical, consider using UUID v7 (time-ordered) or a ULID instead. For most applications, however, UUID v4 performance is perfectly acceptable.
The braces format ({xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx}) is the standard representation in Microsoft environments, including .NET, COM, and Windows Registry entries. Use this format when working with Windows APIs, COM components, or .NET applications that expect GUIDs in this notation.
While most programming languages can generate UUIDs with a single function call, having a dedicated browser tool is useful for quick lookups, testing, and generating batches of UUIDs for seed data or test fixtures without writing any code. It is also accessible to non-developers who need UUIDs for configuration files, spreadsheets, or documentation.
The multiple format options and bulk generation capability make this tool more versatile than a simple one-UUID generator. Whether you need one UUID to paste into a config file or 100 UUIDs to populate a test database, this tool handles both cases with the same simple interface.
Your privacy is our priority. All processing happens entirely in your browser using JavaScript. No files, data, or inputs are ever uploaded to any server. Everything stays on your device, making this tool completely safe to use with sensitive content.
A UUID (Universally Unique Identifier) is a 128-bit identifier formatted as 8-4-4-4-12 hexadecimal characters (e.g., 550e8400-e29b-41d4-a716-446655440000). UUIDs are used as unique keys in databases, session tokens, file names, and anywhere a globally unique identifier is needed without a central authority.
UUID v1 is generated from the current timestamp and the machine's MAC address, making it time-sortable but potentially revealing device information. UUID v4 is randomly generated, making it more private and suitable for most use cases. UUID v4 is the most widely used version.
Theoretically yes, but practically no. UUID v4 has 122 random bits, giving 5.3 x 10^36 possible values. The probability of generating a duplicate is astronomically small — you would need to generate billions of UUIDs per second for billions of years to have a reasonable chance of collision.
Auto-increment IDs are simpler and more compact but expose record counts and are hard to use across distributed systems. UUIDs work across multiple databases and services without coordination, but are larger (16 bytes vs 4-8 bytes) and can hurt index performance. UUID v7 (time-ordered) is a good middle ground.
A ULID (Universally Unique Lexicographically Sortable Identifier) is similar to UUID but designed to be sortable by creation time. It is 26 characters in base32 encoding. ULIDs are useful when you need unique IDs that also sort chronologically, like database primary keys.