Online UUID / GUID Generator
This free, private tool instantly generates cryptographically secure Version 4 UUIDs (Universally Unique Identifiers) directly in your browser. It supports bulk generation, custom formatting, and guarantees that your data is never sent to any server.
What is a UUID / GUID?
A UUID (Universally Unique Identifier), also known in Microsoft ecosystems as a GUID, is a 128-bit label used for information in computer systems. Version 4 UUIDs are generated using random numbers, making it practically impossible for the same identifier to be generated twice.
Example
Format (Standard):
xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx
Output (v4 UUID):
f47ac10b-58cc-4372-a567-0e02b2c3d479
Advantages and Limitations
- Advantages: Can be generated completely independently without a centralized authority, highly secure against collisions, and natively supported by most databases.
- Limitations: UUIDs take up more storage space (128 bits) compared to standard integer IDs (32 or 64 bits), and random UUIDs can cause index fragmentation in some databases.
How to Use
- Enter the number of UUIDs you want to generate in the "Count" field.
- Select your preferred format (Standard with dashes or Compact).
- Choose whether the characters should be uppercase or lowercase.
- Click the "Generate UUIDs" button.
- Click "Copy to Clipboard" to use the generated identifiers in your project.
Common Use Cases
- Database Primary Keys: Generating collision-free, globally unique IDs for database records.
- Session Tokens: Creating secure, unpredictable session identifiers for web authentication.
- API Testing: Supplying dummy unique identifiers when testing endpoints or creating mock data.
- Distributed Systems: Assigning unique reference codes across microservices without relying on a central database sequencer.
Privacy & Security
Your security is our priority. All UUIDs are generated locally using your browser's native crypto.randomUUID() API. No data is tracked, transmitted, or logged on external servers.
Frequently Asked Questions
What is the difference between a UUID and a GUID?
They are essentially the same thing. UUID stands for Universally Unique Identifier, while GUID (Globally Unique Identifier) is Microsoft's implementation of the UUID standard.
Why does this tool use Version 4 UUIDs?
Version 4 UUIDs are generated using random or pseudo-random numbers rather than relying on MAC addresses and timestamps (like Version 1). This makes them much more secure and prevents information leakage.
Can a UUID be generated twice?
While theoretically possible, the probability is practically zero. A Version 4 UUID has 122 random bits, resulting in 5.3 × 1036 possible combinations.