UUID Generator
Generate v4 UUIDs in bulk.
This tool runs entirely in your browser. Your data never leaves your device — nothing is uploaded to our servers.
About UUID Generator
A version 4 UUID is 122 random bits, which is enough that generating a billion per second for a century still leaves collision odds negligible. That property is what makes UUIDs useful: two systems can each mint identifiers with no coordination and safely assume they'll never clash. This generator uses the browser's cryptographic random number source rather than Math.random, which matters if the value is ever used where predictability would be a problem.
When to use UUID Generator
Primary keys created before an insert
Letting the client generate the ID means a record can be referenced immediately, without a round-trip to learn what the database assigned.
Correlation IDs for tracing
Tag a request at the edge and carry the same ID through every service, so one identifier reconstructs the whole path through your logs.
Idempotency keys
Payment APIs use a unique key per attempt so a retried request is not charged twice.
Limitations worth knowing
- Version 4 UUIDs carry no timestamp, so they do not sort chronologically. Sorting by UUID gives you random order.
- As a database primary key, their randomness fragments B-tree indexes and hurts insert performance at scale. UUIDv7 or ULID address this.
- They are 36 characters as text versus 4 bytes for a 32-bit integer — meaningful in large tables and in URLs.
- Unguessable is not the same as access control. Never treat a UUID in a URL as authorisation.
How to uuid generator
- 1
Open the tool — a fresh UUID is generated immediately.
- 2
Generate again for as many as you need.
- 3
Copy the value straight to your clipboard.
- 4
Use lowercase form consistently; UUIDs are case-insensitive but mixing cases breaks naive string comparisons.
Frequently asked questions
Can two generated UUIDs ever be the same?+
In theory yes, in practice no. With 122 random bits you would need to generate about 2.7 × 10^18 UUIDs before reaching a 50% chance of a single collision. For any realistic application, treating them as unique is safe.
Are these random enough to use as security tokens?+
They're generated with crypto.getRandomValues, the browser's cryptographically secure source, so they aren't predictable. Even so, a UUID identifies rather than authorises — a resource reachable by anyone who knows its UUID is not access-controlled, it's just obscure.
Should I use UUIDs as database primary keys?+
It's a real trade-off. You gain client-side generation and no cross-system collisions; you pay in index fragmentation, since random values scatter inserts across the index, and in storage. If you want both, look at UUIDv7 or ULID, which are time-ordered and keep inserts sequential.
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