UUID Generator
Generates UUID v4 random identifiers in standard 36-character string format with an optional compact hex mode (no dashes). Code never leaves your device — formatting and validation run locally in your browser.
Runs on UUID
How to Use the UUID Generator
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Frequently Asked Questions
What is the difference between UUID v4 and v1?
v4 generates cryptographically random identifiers, so every UUID is unpredictable and virtually guaranteed to be unique. v1 generates time-based UUIDs that encode the current timestamp and your device's MAC-derived node value, which makes them sequential and sortable but reveals when each ID was created. Use v4 for database keys, tokens, and anything security-sensitive; use v1 when you need chronologically sortable identifiers.
Are the generated UUIDs really unique? Could there ever be a collision?
Yes, they are RFC 4122 compliant. v4 uses 122 bits of randomness from a cryptographically secure source, so the odds of a collision are astronomically small — roughly 1 in 2^122. Even generating 1 billion UUIDs per second, you would need to run for about 86 years to reach a 50% chance of one duplicate. The tool uses the same industry-standard uuid library that powers millions of databases.
Can I generate UUIDs without dashes or in uppercase?
Yes. The 'Include Hyphens' toggle strips the dashes to produce a 32-character compact hex string, useful for filenames, URLs, or systems that reject the standard format. The 'Capitalize (UPPER)' toggle converts all letters to uppercase. Both options regenerate the entire list instantly and work with either UUID version.
How many UUIDs can I generate at once?
Between 1 and 100 per batch. Use the Quantity slider to pick the count, and every change regenerates a fresh list. You can then copy all of them to the clipboard at once or download the full list as a .txt file.
Which versions exist, and what file does Save List produce?
Two buttons only: v4 (Random) and v1 (Time) - no v3, v5 or v7. Save List downloads uuids-v4.txt or uuids-v1.txt (text/plain, one UUID per line) and the blob URL is revoked 100 ms later.
Does UUID Generator upload my data?
No. Everything runs entirely in your browser using the crypto API — no UUID is ever sent to a server, and no files or data leave your device. You can even use it after disconnecting from the internet once the page has loaded.
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Last updated October 2026