UUID Generator

UUID Generator: Core Features and Principles

When you need to create globally unique identifiers for database records, API endpoints, distributed systems, or files, constructing them manually is prone to collisions and non-compliant with standards. A UUID (Universally Unique Identifier) is a 128-bit string used to generate unique IDs in distributed systems without central coordination. This tool supports the bulk generation of seven RFC-standard UUID versions, from V1 to V7. Each version uses a different generation algorithm, such as time-based V1, random number-based V4, or namespace and name hash-based V3/V5.

Why Choose Our UUID Generator?

• Supports All RFC Standard Versions: Covers seven versions including V1 (timestamp), V3 (MD5 namespace), V4 (random), V5 (SHA-1 namespace), and V6/V7 (new timestamp/random), meeting various tech stack and security requirements.
• Flexible Namespaces and Custom Input: When generating V3/V5 versions, you can directly use predefined DNS, URL, OID, or X500 namespaces, or input a custom UUID as the namespace to generate a deterministic UUID with any name string.
• Controllable Bulk Generation and Formatting: Generate 1 to 100 UUIDs at a time, and freely choose between uppercase or lowercase output formats for easy embedding into code or configuration files.

How to Use

1. Select your required version from the "UUID Version" dropdown menu (e.g., the commonly used random V4).
2. Enter the number of UUIDs you want to create in the "Generate Quantity" field (1-100).
3. If generating V3 or V5 versions, select a standard space (like DNS) in "Predefined Namespace", or enter a valid UUID in the "Custom Namespace" field, and input the corresponding string (like a domain name) in the "Name" field.
4. Click the "Generate" button, and the results will be displayed as text, one per line.
5. You can select all the generated UUID text and copy it directly for use.

Frequently Asked Questions (FAQ)

Q: What is the difference between UUID V4 and V1?
V4 is based on random number generation. It is completely random with an extremely low probability of collision, making it suitable for most scenarios that do not require chronological order. V1 is generated based on a timestamp, MAC address, and sequence number, ensuring monotonic increase over time. It is ideal for logs or records that need to be sorted by time, but it may leak host information.

Q: What is a Namespace and what is it used for?
A namespace is itself a UUID. When generating V3 (MD5) or V5 (SHA-1) UUIDs, it is hashed together with a "name" (such as a URL or domain) to generate a different but deterministic (reproducible) UUID for the same name across different namespaces. For example, a V5 UUID generated for "example.com" using the DNS namespace will always result in the exact same value, regardless of where or when it is calculated.

Important Notes

When using V3 or V5, you must provide a valid namespace UUID and a name string. Custom namespaces must follow the standard UUID format (8-4-4-4-12 hexadecimal digits). For V1/V6/V7, you can optionally fill in a timestamp, node ID, and clock sequence; if left blank, the current system time and default values will be used. Please note that V3 uses the MD5 hash algorithm, which has weaker collision resistance than SHA-1. In scenarios with extremely high security requirements, V5 is highly recommended.

Technical Notes & Best Practices

When selecting a UUID version, you need to balance uniqueness, readability, sorting requirements, and security. For scenarios requiring global randomness without sorting needs (like session IDs or temporary tokens), V4 is the most common choice. If you need to generate a permanent and verifiable unique ID for the same resource (like a user email), you should use V5 and agree upon a namespace (such as a company-specific UUID). A typical example: using the DNS namespace (6ba7b810-9dad-11d1-80b4-00c04fd430c8) and the name "user@example.com", the UUID generated via the V5 algorithm will always be "5df41881-3aed-3515-88a7-2f4a814cf09e". When bulk generating for test data, note that the limit is 100 per request; for more, simply repeat the operation.