UUID / ULID Generator

Generate UUIDs (v1, v4, v7) and ULIDs in bulk. UUID v7 is timestamp-prefixed and lexically sortable — great for database keys.

Version Count Uppercase Include hyphens

Generate UUID v1 and UUID v4 identifiers in bulk

UUIDs (universally unique identifiers) are 128-bit values used as primary keys, request IDs, idempotency tokens, and correlation identifiers. They allow distributed systems to mint identifiers without coordinating, which is why almost every modern API and database supports them. This page generates v1 (time-based) and v4 (random) UUIDs in batches so you can seed databases, fixtures, log data, and scratch scripts without reaching for the command line.

Choose the version you need. v4 is right for almost every new use case; v1 is useful when you specifically want time ordering.
Set the count, generate, then copy the list into your code, fixture, or terminal.
For uniqueness audits, paste candidates into a JSON array and use the JSON tool to detect duplicates quickly.
Use the format your downstream system expects: with hyphens for most APIs, without hyphens for some legacy systems.

Why different ID schemes exist

UUIDs are attractive because they can be generated without central coordination. That helps in distributed systems, offline-capable clients, asynchronous pipelines, and edge workloads where an ID may need to exist before a database write happens.

But the version still matters. v4 is simple and random yet unfriendly to some B-tree write patterns. v1 carries time and node information. v7 and ULID push harder toward time ordering and database locality. Choose the version from the storage, ordering, privacy, and interoperability requirements rather than generating one by habit.

When UUIDs are not the best answer

If your application is a straightforward server-side system with modest write volume, auto-increment IDs can still be perfectly reasonable. UUIDs bring index overhead, lower readability, and more friction in logs and debugging.

That is why long-form text is useful here. It lets the page explain when UUIDs or ULIDs make sense, and when a simpler identifier strategy is actually better engineering.

Best use cases

Generating sample primary keys for database seed scripts and fixtures.
Creating idempotency keys for HTTP requests and webhook tests.
Producing correlation IDs for log searches and tracing experiments.

Common mistakes to avoid

UUID v4 is not strictly guaranteed unique, but the collision probability is negligible for practical workloads.
UUIDs are 36 characters with hyphens, which can be wasteful as URL segments. Consider shorter encodings if URL length matters.
Do not derive secrets from UUIDs. They are unique, not unguessable in a cryptographic sense.

How this tool works

Implementation: Browser crypto.getRandomValues and project TypeScript implementations for supported UUID versions
Data path: Input is processed in the current browser tab. Tool input is not submitted to a DevHelper Tools application server.
Independent check: Parse the result with the target platform and confirm the selected version matches ordering, privacy, and storage requirements.

Verify before production use

A successful conversion or generated snippet is not proof that it matches your runtime. Check the output against an independent implementation, test one known edge case, and record the environment or standard version you validated.

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FAQ

Should I use UUID v1 or v4?

Use v4 by default. Use v1 only when you need rough time ordering and accept that v1 leaks the generator MAC address and timestamp.

Are these generated UUIDs cryptographically random?

They are produced by the browser`s built-in random source, which is appropriate for identifiers. They are not designed to replace dedicated cryptographic key generation.

Can I use UUIDs as database primary keys?

Yes, and they are common in distributed systems. Watch out for write performance on B-tree indexes; use ULIDs or v7 if write-order locality matters.