UUID / GUID Generator
Generate UUID v1, v4, and v7 with custom formats
Frequently Asked Questions
What is a UUID / GUID?
A UUID (Universally Unique Identifier) is a 128-bit value usually rendered as 32 hexadecimal characters with hyphens, e.g., 550e8400-e29b-41d4-a716-446655440000. GUID is Microsoft's name for the same concept. UUIDs can be generated independently across distributed systems with virtually no collision risk, making them popular as database primary keys and resource IDs.
When should I use UUID v1, v4, or v7?
v1 encodes a timestamp and MAC address — sortable by time but may leak hardware details. v4 is fully random and the most widely used. v7 is the newer time-ordered variant that keeps the randomness of v4 while allowing efficient index ordering, making it a strong default for database keys. Use v4 for public identifiers and v7 when insert order matters.
How many UUIDs can I generate at once? Which formats are supported?
You can generate thousands at a time. Output formats include the standard dashed form, compact (no dashes), braced GUID form, upper/lower case toggle, and quoted variants for pasting directly into code.
Are the generated UUIDs really unique?
v4 uses cryptographically secure random numbers; the theoretical collision probability is astronomically low (you would need around 2^61 UUIDs to hit a 50% chance of a single duplicate). In practice they are treated as unique. For critical systems you should still rely on a database uniqueness constraint as a safety net.
Does this leak any private information? Is my data safe?
DevToolkit generates UUIDs locally using the browser's crypto.getRandomValues API (for v4) and the local clock (for v1/v7). Nothing is sent to a server and no history is stored. v1 can expose node/clock details — choose v4 or v7 if that is a concern.
How does UUID compare with auto-increment IDs or nanoid?
Auto-increment IDs are short and sortable but leak row counts and require database coordination. nanoid is typically shorter (21 chars) and URL-friendly, with collision odds comparable to UUID v4. UUID has the broadest ecosystem support — virtually every language has a built-in implementation. Pick based on your display, storage, and sortability needs.