UUID generator
Cryptographically randomGenerate UUIDs in bulk: random version 4, time-ordered version 7 (sorts by creation time, good for database keys) or ULIDs, from your browser's cryptographic random number generator.
Fill in the fields to see the result.
How to use it
- Choose v4, v7 or ULID and how many (up to 1,000).
- Press Generate for a fresh batch.
- Copy them, or download a CSV.
Details
- v4
- 122 random bits (RFC 9562)
- v7
- 48-bit Unix millisecond timestamp + random bits; sorts by time
- ULID
- 26 Crockford Base32 characters, time-sortable
- Source
- crypto.getRandomValues / crypto.randomUUID
Questions
Should I use UUID v4 or v7?
v7 for database primary keys: it sorts by creation time, so inserts stay close together in indexes. v4 when you don't want the creation time visible in the ID.
Can two UUIDs collide?
In practice, no. With 122 random bits you'd need to generate about a billion v4 UUIDs a second for decades before a collision became likely.
Are these UUIDs safe to use as secrets?
They're unpredictable, but UUIDs are designed as identifiers, not tokens. For session tokens or API keys use a dedicated random token of 128 bits or more.
What is a ULID?
A 128-bit ID written as 26 characters that sorts by time, like 01HF…. It's shorter than a UUID string and safe in URLs.
Is my input sent anywhere?
No. It is processed by code running in this tab. Nothing is uploaded, logged or saved; tokens, hashes and text are never put in the page address.
Can an AI agent use this?
Yes. The same function is a tool on our free MCP server at tools.cuelark.com/mcp, so ChatGPT, Claude or Cursor get exactly the answer this page shows. 'Copy MCP call' gives you the arguments.