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Guide
About the UUID Generator
A UUID (Universally Unique Identifier), also called a GUID, is a 128-bit value written as 36 characters — 32 hexadecimal digits in five groups separated by hyphens, like f47ac10b-58cc-4372-a567-0e02b2c3d479. UUIDs let independent systems generate identifiers that are effectively guaranteed never to collide, without coordinating through a central database. That makes them ideal for primary keys, request IDs, file names, and distributed systems.
This generator produces every current UUID version — random v4, time-ordered v7 and v6, classic v1, and name-based v5 and v3— plus ULIDs and NanoIDs, using your browser's cryptographically secure random number generator. Paste an ID into the inspector to see its version and, for time-based IDs, exactly when it was made.
UUID v4 vs. v7 — which should I use?
v4 is fully random and the most widely used. Its downside is that random IDs scatter across a database index, which can hurt insert performance at scale. v7is newer and embeds a Unix millisecond timestamp in its leading bits, so freshly generated v7 UUIDs sort roughly in creation order. That makes them far friendlier as database primary keys while still being globally unique. If you're choosing today and your database supports it, v7 is often the better default; v4 remains a safe, universal choice.
Name-based UUIDs (v5 and v3)
Sometimes you want the same ID every time for the same thing — a stable ID for a URL, an email address or a product code, computed independently by different systems. v5 hashes a namespace UUID and a name with SHA-1; v3 does the same with MD5. Use one of the standard namespaces (DNS, URL, OID, X.500) or your own, and paste many names at once to get one UUID per line.
ULID, NanoID and Snowflake IDs
A ULID holds the same 128 bits as a UUID but is written as 26 Crockford Base32 characters and sorts by time; the inspector converts between the two. NanoID trades structure for brevity: 21 URL-safe characters carry about as much randomness as a v4 UUID. Snowflake IDs — 64-bit integers used by X (Twitter), Discord and others — embed a timestamp, which the inspector decodes.
How unique are they, really?
A v4 UUID has 122 random bits. The number of them you'd need to generate before a collision becomes likely is so large that, in practice, you can treat them as unique forever. You do not need to check for duplicates in normal applications.
How to use it
- 1Choose the type — v4 for pure randomness, v7 for database keys, v5 for stable name-based IDs.
- 2Set how many you want, or enter the names for v5/v3.
- 3Pick the format, case, quotes and separator your code needs.
- 4Copy one, copy all, or download them as a text file.
Frequently asked questions
What is the difference between a UUID and a GUID?
They are the same thing. GUID (Globally Unique Identifier) is Microsoft's term; UUID is the standardized name. The format and guarantees are identical.
Are these UUIDs cryptographically secure?
The randomness comes from the browser's crypto.getRandomValues, which is a cryptographically secure source. That said, UUIDs are identifiers, not secrets — don't use one as a password or token on its own.
Should I use UUID v4 or v7 for a database primary key?
v7 is usually better for primary keys because its time-ordered layout keeps index inserts sequential, avoiding the fragmentation random v4 keys can cause. Use v4 when you specifically want unordered, opaque IDs.
Can I generate UUIDs in bulk?
Yes — up to 10,000 at once. Choose quotes and commas to paste them straight into code or a SQL IN list, or download them as a file.
Are bulk v7 UUIDs in order?
Yes. Many v7 UUIDs are created within the same millisecond, so the random part counts upward within each millisecond (as RFC 9562 recommends). A batch sorts in the order it was generated. ULIDs work the same way.
How do I find out when a UUID was created?
Open “Inspect an ID” and paste it. v1, v6 and v7 UUIDs, ULIDs and Snowflake IDs carry a timestamp, which is decoded; v4 and v5 contain none.
Is generation done offline?
Yes. Everything runs in your browser with no network calls, so you can generate UUIDs even offline.