Ten UUIDs are on screen the moment the page loads - just hit Copy. Bulk-generate up to 1000, or paste a UUID to decode it (free, no signup)
Paste a UUID you already have and this reports its version and variant. UUIDs that carry a timestamp, such as v1, v6 and v7, also show the embedded creation time. Uppercase, hyphen-free and brace-wrapped input is accepted as-is.
What each field means and how to use it. Click to expand.
v4 is a fully random UUID with 122 bits of randomness. v7 is time-ordered, carrying a 48-bit Unix millisecond timestamp in its first bits so values increase monotonically. Random v4 primary keys can fragment indexes, so v7 is increasingly preferred for databases. v1 is the older scheme built from a 100-nanosecond timestamp counted from 1582-10-15 plus a node ID; use it when an existing system expects it. This tool fills the node ID with random bytes (with the multicast bit set) rather than a real MAC address, so nothing identifies your machine.
Paste a UUID and the tool reads back its canonical form (lowercase 8-4-4-4-12), version and variant, because the 13th character encodes the version and the top bits of the 17th encode the variant. v1, v6 and v7 embed a timestamp, so the creation time is shown in UTC and in your local time. The all-zero nil UUID and the all-f max UUID are recognised too.
How many to generate at once (1-1000). Handy for test data or seed inserts; bulk-generate and save as .txt.
Combine uppercase, hyphen removal and brace wrapping. Braced form (e.g. {550e8400-...}) is used by some Microsoft-style GUID notations. Choose what fits your target.
Randomness comes from crypto.getRandomValues (cryptographically secure). For v4 the tool uses crypto.randomUUID when the browser supports it. Results are shown only on the page and never sent to a server.
v4 is fully random; v7 is time-ordered with a leading timestamp. Because v7 sorts in creation order, it tends to help database primary keys and indexes.
With 122 bits of randomness the practical collision probability is extremely low, but where uniqueness is critical, pair it with a database unique constraint.
No. Generating, copying and saving all happen in your browser, and results are never sent.
If you have no specific requirement, v4 (fully random) is fine. Choose v7 when you want values to sort in creation order, such as database primary keys. v1 is the older scheme built from a timestamp and a node ID, useful when you need compatibility with an existing system.
Yes. Paste it into the UUID inspector on this page and it reports the canonical form, version and variant. UUIDs that carry a timestamp, such as v1, v6 and v7, also show the embedded creation time.