What is a UUID v4?
A Version 4 UUID is a 128-bit identifier generated using random numbers according to RFC 4122 specifications.
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UUID & GUID Generator - Generate v4 UUIDs | 1ClickTools
Generate random, cryptographically secure UUID v4 (Universally Unique Identifiers) and GUIDs in bulk. 100% local browser generation.
About This Tool
Universally Unique Identifiers (UUIDs), also known as Globally Unique Identifiers (GUIDs), are 128-bit numbers used in software development to uniquely identify resources across distributed systems without requiring a central coordinator. A Version 4 UUID relies on random number generation, providing a 1 in 2^122 probability of collision. Our browser-native UUID Generator utilizes the Web Cryptography API (crypto.getRandomValues()) to generate cryptographically strong, non-predictable v4 UUIDs. You can generate single UUIDs or bulk batches (up to 1,000 UUIDs at once), choose uppercase or lowercase formatting, and toggle hyphens. Because random number generation takes place directly within local hardware memory, generated UUIDs are completely private and never logged on cloud servers. Copy bulk UUIDs to your clipboard or export as a text file in seconds.
Frequently Asked Questions
What is the probability of two UUID v4s colliding?
The collision probability is so infinitesimally small (1 in 2^122) that generating billions of UUIDs per second for decades would yield no duplicates.
Is my generated UUID saved on a web server?
No. 1ClickTools generates UUIDs 100% locally in your browser memory.
What is the difference between UUID and GUID?
UUID (Universally Unique Identifier) is the open standard term; GUID (Globally Unique Identifier) is Microsoft's terminology for the same standard.
Are UUIDs generated with Web Crypto API secure for database primary keys?
Yes! crypto.getRandomValues() uses hardware-level entropy for secure random numbers.
Works on mobile browsers?
Yes, fully compatible across mobile Safari, Chrome, Edge, and Firefox.
Can I generate UUIDs without hyphens?
Yes, uncheck 'Include Hyphens' to output 32-character hexadecimal strings.
Can I export bulk UUIDs as a text file?
Yes, click 'Download .txt' to save generated UUID batches.
Is any software installation required?
No, works directly in your web browser.
Is 1ClickTools UUID Generator free?
Yes, 100% free with no limits.