Developer tool
UUID and Random String Generator
Generate UUID v4 and v7 in bulk, format them your way, create random strings from hex, base62 or custom sets, and parse any UUID.
Free, no sign-up. Runs in your browser; nothing is uploaded.
UUID generator
Random string generator
Validate or parse a UUID
Paste a UUID to see its version, variant and, for version 7, the embedded timestamp.
How to use the uuid and random string generator
Generating identifiers
Choose a type, set how many you need (up to 1000) and press Generate. The result appears in the box below, ready to copy or download as a text file.
Which UUID version fits
- Version 4 is 122 random bits. It is the safe default for tokens, request IDs, file names and anything that should not reveal order or time.
- Version 7 puts a 48-bit Unix millisecond timestamp first, then random bits, as defined in RFC 9562. IDs sort by creation time, which makes them a much better database primary key than v4: index inserts stay sequential instead of scattering across the tree.
- Nil is all zeros. Use it as a placeholder, never as a real identifier.
Formats for different tools
- Lowercase with hyphens is the canonical text form.
- Uppercase is common in Windows tooling and some legacy systems.
- Without hyphens saves space and suits URLs or compact columns.
- Braces
{...}match .NET and the registry;urn:uuid:matches XML and RFC contexts.
Pick the output format to paste straight into your project: one per line for a text file or SQL import, comma separated for a quick list, or a JSON array for code and fixtures.
Random strings
The second section produces random strings of a length you choose from a character set:
- Alphanumeric and base62 are good for API keys and short codes.
- Hex matches the format of hashes and many secret tokens.
- Base64url is safe inside URLs and file names.
- Numeric is useful for test data, though it carries few bits per character.
- Custom lets you remove look-alike characters or limit output to a specific alphabet.
For secrets, aim for at least 128 bits: 22 base62 characters, 32 hex characters or 22 base64url characters.
Checking an existing UUID
Paste any UUID into the validate box. You will see whether it is well formed, its version and variant, and for v7 the exact creation time embedded in it. This is handy when debugging logs or working out which record came first.
Frequently asked questions
Should I use UUID v4 or v7?
Use v4 when you only need an unguessable identifier. Use v7 for database primary keys: its leading timestamp makes new rows land at the end of the index, which keeps inserts fast and lets you sort by creation time.
Can two generated UUIDs collide?
A v4 UUID has 122 random bits, so a collision is astronomically unlikely: you would need to generate billions per second for decades to have a realistic chance. v7 has 74 random or counter bits per millisecond, which is also ample.
Does a v7 UUID leak when it was created?
Yes. The first 48 bits are the creation time in milliseconds, and anyone can read it with the parser on this page. Use v4 for identifiers where creation time must stay private.
Are these generated securely?
Yes. All randomness comes from crypto.getRandomValues, and random strings use rejection sampling so no character is more likely than another. Nothing is sent to a server.
What is the nil UUID?
The nil UUID is 00000000-0000-0000-0000-000000000000. It is a reserved value often used as an empty or placeholder identifier.
What do the braces and urn:uuid: formats do?
Braces are the style used by Microsoft tools and the Windows registry. The urn:uuid: prefix is the standard URN form from RFC 9562, used in XML and some protocols.