Generate cryptographically random v4 UUIDs in bulk.
51aecc31-15ee-43d5-9cc9-b155f43d91c3A UUID (universally unique identifier, called a GUID in the Microsoft world) is a 128-bit value written as 36 characters of hex and hyphens, like 123e4567-e89b-42d3-a456-426614174000. Version 4 UUIDs are generated from random bits — 122 of them — which makes the chance of two ever colliding so small that systems around the world mint them independently with no coordination and no central registry.
This free uuid generator online creates v4 UUIDs using your browser’s cryptographically secure random number generator (crypto.randomUUID), not a seeded pseudo-random fallback, so the identifiers are safe to use as database keys, request IDs, idempotency keys, or test fixtures. Generation happens entirely on your machine and the results are not stored or transmitted.
You can generate up to 100 UUIDs at once and shape the output to match your destination: keep or strip the hyphens, switch to uppercase, or wrap each value in braces for the {guid} style used in Windows registries and some .NET tooling. Copy a single value with one click or grab the whole batch newline-separated with Copy all — useful for seeding a database or filling a spreadsheet column.
Enter how many UUIDs you need in the Count field, from 1 to 100. A first batch is generated automatically when the page loads.
Toggle the Hyphens, Uppercase, and Braces checkboxes to match the format your system expects. Formatting applies instantly to the current batch.
Hit Regenerate to mint a fresh batch of cryptographically random v4 UUIDs at the chosen count.
Use the copy icon next to any UUID to copy it alone, or Copy all to put the entire list on your clipboard, one per line.
Statistically, yes. A v4 UUID has 122 random bits, so you would need to generate about 2.7 quintillion UUIDs to reach even a 50 percent chance of a single collision. For practical purposes duplicates do not happen.
Nothing meaningful — GUID is Microsoft’s name for the same 128-bit identifier format. GUIDs are conventionally written in braces or uppercase in some Windows contexts, which this tool can produce with the Braces and Uppercase options.
The version digit (the 4 at the start of the third group) indicates how the UUID was generated. Version 4 means random: all bits except the version and variant markers come from a random source. Other versions derive from timestamps or name hashing.
They are generated with a cryptographically secure random source, which is the right foundation. That said, dedicated secret tokens with more entropy are a better choice for security credentials; UUIDs are designed as identifiers, not secrets.
It is common and works well when you need keys generated by distributed clients or want to avoid leaking row counts. The trade-offs are larger index size and worse insert locality than sequential integers; some databases mitigate this with UUID-optimized column types.
ReSlug generates collision-resistant short codes for every link, with no guessable patterns.