UUID Generator
Generate random UUID v4 identifiers instantly. Bulk generate, copy with one click, and choose your preferred format. Free and private.
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Free Online UUID Generator
Need a unique identifier? SmarterSources' UUID Generator creates random version 4 UUIDs instantly. UUIDs (Universally Unique Identifiers) are 128-bit identifiers that are guaranteed to be unique across space and time, making them perfect for database primary keys, session tokens, file names, and distributed systems. Everything runs in your browser — no data is sent to any server.
What is a UUID v4?
A UUID v4 (version 4) is generated using random or pseudo-random numbers. The standard format is xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx, where x is a random hexadecimal digit and y is one of 8, 9, a, or b. The 4 indicates the UUID version. With 122 random bits, the probability of generating two identical UUIDs is astronomically small.
Bulk Generation
Need more than one? The bulk generator creates up to 1,000 UUIDs at once, displayed one per line for easy copy-pasting. All generated UUIDs respect your chosen format (with or without dashes, uppercase or lowercase).
Format Options
Standard format includes dashes as separators (e.g., 550e8400-e29b-41d4-a716-446655440000). No Dashes removes the hyphens for a compact 32-character string. Uppercase and Lowercase control the letter casing of the hexadecimal digits.
Frequently Asked Questions
Are these UUIDs truly unique?
Version 4 UUIDs are generated using random numbers. With 122 random bits, there are over 5.3 x 10^36 possible values. The probability of generating a duplicate is so low that it is considered negligible for all practical purposes. You would need to generate about 2.71 quintillion UUIDs to have a 50% chance of a single collision.
What is the difference between UUID and GUID?
UUID (Universally Unique Identifier) and GUID (Globally Unique Identifier) are essentially the same thing. UUID is the term used in the RFC 4122 standard and in most programming ecosystems. GUID is the term used primarily in Microsoft technologies. The format and generation methods are identical.
Should I use dashes or no dashes?
The standard UUID format includes dashes (8-4-4-4-12 pattern), and this is what most systems expect. Some databases and APIs accept the compact form without dashes. Use the format that your target system requires. When in doubt, use the standard dashed format.
Can I use UUIDs as database primary keys?
Yes. UUIDs are commonly used as primary keys, especially in distributed systems where auto-incrementing integers are impractical. They prevent ID collisions when merging data from multiple sources. The trade-off is that UUIDs are larger (16 bytes vs 4-8 bytes for integers) and can be slightly slower for indexed lookups.
How is the UUID generated?
This tool uses the browser's built-in crypto.randomUUID() when available (supported in all modern browsers). As a fallback, it uses crypto.getRandomValues() or Math.random() to generate cryptographically strong random values, ensuring each UUID is unpredictable and unique.
Is my data private?
Absolutely. UUIDs are generated entirely in your browser using JavaScript. No data is sent to any server. The history list is stored only in your browser's memory for the current session and is cleared when you close the tab.