在线免费UUID生成器
为您的项目生成唯一的UUID v4标识符。
A UUID (Universally Unique Identifier) is a 128-bit identifier formatted as xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. UUIDs are designed to be globally unique without a central coordinator — two independently generated UUIDs will almost never collide, even across billions of records.
UUID versions explained
- v4 (random): 122 bits of randomness — the most common choice, best for new IDs with no ordering requirement
- v1 (timestamp): encodes the current timestamp — sortable by creation time but reveals when and roughly where it was generated
- v5 (namespace + name): a SHA-1 hash of a namespace UUID and a name string — deterministic, so the same input always produces the same UUID
When to use UUIDs
UUIDs are used as primary keys in distributed databases, session tokens, file identifiers, API resource IDs, and anywhere a unique identifier must be generated without coordination between servers. v4 is the safe default for most applications.
Frequently Asked Questions
What is a UUID and when should I use one?
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). Use UUIDs as database primary keys, API resource IDs, and session tokens where uniqueness without central coordination is needed.
What is the difference between UUID v1 and v4?
UUID v1 includes a timestamp and MAC address — its creation time can be extracted. UUID v4 is fully random — it contains no traceable information, making it preferred for privacy-sensitive use cases.
Are generated UUIDs truly unique?
UUID v4 generates 2^122 possible values (≈5.3 × 10^36). The probability of two randomly generated UUID v4s colliding is astronomically small — generating 1 billion UUIDs per second for 100 years would have a ~50% chance of one collision.
What is UUID v5?
UUID v5 generates a deterministic UUID from a namespace UUID and a name using SHA-1 hashing. The same namespace + name always produces the same UUID — useful for creating stable identifiers for URLs or domain objects.
Can I generate UUIDs in uppercase format?
Yes. Toggle the uppercase option to output UUIDs in UPPERCASE hex (550E8400-E29B-41D4-A716-446655440000). Both forms are valid — case doesn't affect uniqueness.
Is the UUID生成器 free to use?
Yes, the UUID生成器 on Allio Tools is completely free with no sign-up or registration required. It works directly in your browser.
How does the UUID生成器 work?
为您的项目生成唯一的UUID v4标识符。 No data is sent to a server — everything runs locally in your browser for maximum privacy and speed.
Do I need to install anything to use the UUID生成器?
No installation needed. The UUID生成器 runs entirely in your web browser on any device — desktop, tablet, or mobile.
Is my data safe when using the UUID生成器?
Completely safe. The UUID生成器 processes everything locally in your browser. No input data, results, or usage information is ever transmitted to or stored on any server.
Does the UUID生成器 work offline?
After the page loads for the first time, the UUID生成器 works without an internet connection for all client-side processing. Tools that fetch live external data (such as DNS or network lookups) require an active connection.
Can I use the UUID生成器 output in commercial projects?
Yes. The UUID生成器 is a utility tool and its output carries no licensing restrictions. You are free to use results in any project, commercial or personal.
Does the UUID生成器 follow official standards?
Yes. The UUID生成器 is built to comply with the relevant industry standard or specification for this utility type. If you encounter an unexpected result, verify your input against the specification — edge cases outside the standard may produce undefined behaviour.
Does the UUID生成器 work on all browsers?
Yes. The UUID生成器 is built with standard browser APIs and works on all modern browsers including Chrome, Firefox, Safari, and Edge — on both desktop and mobile. No plugins, extensions, or third-party software are required.
How do I save or export my results from the UUID生成器?
Select and copy the result text to paste into any document or app. For image tools, a Download button saves the file directly to your device. Your browser's built-in screenshot function also captures results quickly. No account or login is required.