How to generate UUIDs
- Choose v4 (random) or v7 (time-ordered) and how many you need, up to 5,000.
- Tick Uppercase, No hyphens or {Braces} to match your format.
- Click Generate, then Copy all or Download as a text file.
- For short IDs, set length, count and alphabet under Random strings and click Generate.
What you can do with UUID & Random ID Generator
- UUID v4 and v7
- Create fully random v4 UUIDs, or v7 UUIDs that start with a millisecond timestamp and sort in creation order.
- Bulk generation
- Produce up to 5,000 UUIDs at once, one per line, and download them as a .txt file for seeding or testing.
- Format options
- Output uppercase, remove hyphens, or wrap in braces for Microsoft-style GUIDs used in registry keys and .NET code.
- UUID inspector
- Paste any UUID to see its version and variant, plus the creation time encoded in v1 and v7 UUIDs.
- Random string generator
- Make nanoid-style IDs up to 512 characters with URL-safe, alphanumeric, hex, digits-only, no look-alike or custom alphabets.
- Cryptographically secure
- Uses crypto.randomUUID and crypto.getRandomValues with unbiased sampling, and shows the entropy of each random string.
UUID v4 vs v7 and collision probability
A UUID (universally unique identifier), called a GUID in Microsoft ecosystems, is a 128-bit value written as 32 hex digits in the 8-4-4-4-12 pattern. Version 4 UUIDs contain 122 random bits, so collisions are vanishingly unlikely: you would need to generate around 2.7 quintillion of them for a 50% chance of a single duplicate. That's why they're used as database keys, request IDs and file names without any central coordination between the systems creating them.
UUID v7, standardized in RFC 9562 in 2024, puts a Unix millisecond timestamp in the first 48 bits followed by random data. Because new values sort after older ones, v7 keys keep database indexes compact and inserts fast, which makes them a better default for primary keys than v4 in PostgreSQL, MySQL and similar systems. The trade-off is that a v7 UUID reveals roughly when it was created. For short public IDs, a 21-character URL-safe random string offers about 126 bits of entropy, comparable to a v4 UUID.
Frequently asked questions
Are these UUIDs generated securely and privately?
Yes. They're created in your browser with the Web Crypto API's cryptographically secure random number generator, the same source used for encryption keys. Nothing is requested from or logged on a server, so the IDs are known only to you.
Should I use UUID v4 or v7?
Use v7 for database primary keys and anything you'll sort or index, because values are time-ordered and keep indexes efficient. Use v4 when you don't want the ID to reveal its creation time, such as public tokens or identifiers shared outside your system.
What's the difference between a UUID and a GUID?
They're the same thing. GUID is Microsoft's name for a UUID. GUIDs are often written in uppercase and wrapped in braces, like {3F2504E0-4F89-11D3-9A0C-0305E82C3301}, which you can produce here with the Uppercase and {Braces} options.
Can two generated UUIDs ever be the same?
In theory yes, in practice no. Generating a billion v4 UUIDs every second, it would take about 85 years to reach a 50% chance of one duplicate. v7 UUIDs created in the same millisecond here also use an incrementing counter to stay unique and in order.
Can I get UUIDs without hyphens?
Yes. Tick No hyphens to get 32-character hex strings, a format some databases and URLs prefer. You can combine it with Uppercase, and the options apply to every UUID in the generated list at once.