Bulk Generating a Batch of UUIDs

Bulk Generating a Batch of UUIDs for Test Fixtures

Seeding test fixtures, pre-populating a set of IDs before a data import, or just needing more than one identifier at a time turns a single-UUID generator into a bottleneck fast. Clicking a button once for every value you need does not scale past a handful of rows. This tool's Regenerate All action produces a fresh v1, v4, and v7 identifier together in one click, entirely in your browser, which covers the common case of needing several UUIDs quickly without wiring up a script for a one-off task.

What Regenerate All actually produces

Every click of Regenerate All runs the browser's CSPRNG three separate times, once each for v1, v4, and v7, and replaces all three displayed values at once. None of the three shares any randomness with the others; each is an independent draw seeded from the platform's own random source,¹ so generating them together is a convenience, not a shortcut that weakens any individual value.

The format toggle above the three rows applies to all three values simultaneously, so switching to No Hyphens or Braces before copying reformats every row at once instead of requiring you to reformat each identifier individually. That matters most when you are pulling several values in a row for a fixture file that needs one consistent format throughout.

Copying more than one value per click

Each row has its own Copy button, so building a batch of, say, five UUIDs for a fixture file means clicking Regenerate All, copying the value you need, clicking Regenerate All again, and repeating. That is a manual loop rather than a true bulk-export feature, worth knowing before you assume this page can produce a list of a hundred identifiers in one action.

Where bulk generation actually gets used

Pre-populating a set of IDs before a database import is one of the more common reasons to want several UUIDs at once. Rather than letting an import script or a database default generate each identifier at insert time, some workflows need to know the ID values ahead of time, to cross-reference them in a separate related table, or to hardcode them into a test fixture that other code depends on staying stable across test runs.

Test fixtures follow the same pattern. Testing frameworks that support fixtures, such as Rails' ActiveRecord fixtures, are explicit that the entire point of a fixture is a stable, predictable identifier rather than one that changes from run to run,² and a test suite that seeds five users, ten orders, and twenty line items needs a fixed identifier for each row so foreign-key relationships between fixture files stay consistent every time the suite runs, rather than regenerating randomly and silently drifting between runs. Generating those IDs here, once, and pasting them into the fixture file gives you that stability without hardcoding an ad hoc string that only looks like a UUID.

Why v4 usually fits fixture data better than v7

For fixture and seed data specifically, v4 is usually the more sensible pick over v7, since fixture rows rarely need to sort in creation order and a v7 identifier's embedded timestamp would just record whenever you happened to generate the fixture file, information that has no bearing on the scenario the fixture is meant to represent. Reaching for v4 by default here also keeps the choice consistent with how most test frameworks already treat fixture IDs: arbitrary, stable labels rather than meaningful data.

Why generating many values here stays entirely local

Generating dozens of UUIDs one Regenerate All click at a time never sends a single request to a server. Every value comes from your browser's own CSPRNG, running inside the page you already have open,³ so there's no rate limit, no API key, and no network round trip slowing down a workflow that might otherwise involve pinging an external endpoint for every ID.

That local generation is also why this approach scales fine for a modest batch, a handful to a few dozen identifiers for a fixture file or a manual import list, but is not the right tool for generating thousands of IDs programmatically. At that scale, calling crypto.randomUUID() directly in a script, in a loop, is faster and less error-prone than copying values out of a browser tab one click at a time.

Choosing between this page and a script

Either path draws from the same underlying CSPRNG, so a batch generated here and a batch generated by a script carry identical randomness guarantees; the only real difference between them is convenience at scale, not the quality of the values themselves. Neither approach is more correct than the other, and switching from one to the other partway through a project changes nothing about the identifiers you already generated.

A rough rule of thumb: reach for this page when you need a handful of values for a one-off task and would rather not open an editor at all, and reach for a script the moment the count climbs into the hundreds or the generation needs to run automatically as part of a build or seed step.

When to use this

Use this guide whenever you need a handful of fresh identifiers quickly, to seed test fixtures, pre-populate import IDs, or fill in placeholder values by hand, without writing a script for a one-off task.

Examples

Before: a test fixture file needs five distinct, stable user IDs that will not change between test runs.

Clicking Regenerate All five times and copying the V4 value each time produces five independent UUIDs you can hardcode directly into the fixture file, with no coordination needed between them.

Before: an import script needs to know each row's primary key ahead of time so it can reference those IDs in a related table.

Generating and copying a V4 value per row here, before running the import, gives you a fixed ID to embed in both the primary import and the related table's foreign-key references, rather than letting the database assign one you would have to look up afterward.