In1.

UUID generator

Generate cryptographically random UUID version 4 identifiers, one at a time or hundreds at once. Choose hyphens and casing, then copy the whole batch with a click — all produced securely in your browser.

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How to use UUID Generator

  1. 1

    Set the quantity

    Choose how many UUIDs you want, from one to the maximum.

  2. 2

    Pick a format

    Toggle hyphens and choose lower or upper case to match your system.

  3. 3

    Generate

    Click generate to create a fresh batch of cryptographically random version 4 UUIDs.

  4. 4

    Copy them

    Copy the whole batch with one click and paste it wherever you need.

What a UUID is and why it is useful

A UUID, or universally unique identifier, is a 128-bit value written as a string like 550e8400-e29b-41d4-a716-446655440000. Its purpose is to give something an identifier that is, for all practical purposes, guaranteed never to collide with another one — even if it was generated on a different machine, in a different system, with no coordination between them. That property makes UUIDs the default choice for primary keys in distributed databases, identifiers for files and records, correlation IDs in logs and traces, idempotency keys for API requests, and anywhere two systems need to agree on a name for something without asking a central authority for the next number. Because the space of possible version 4 UUIDs is astronomically large, the chance of two randomly generated ones matching is so small it can be safely ignored. This tool produces them on demand, so you can grab a fresh identifier whenever you need one without writing a line of code or running a script.

Cryptographically random version 4 UUIDs

There are several UUID versions, and version 4 — the kind this tool generates — is the one built almost entirely from random data. That randomness is what gives it its uniqueness and also makes it unpredictable, which matters when an identifier should not be guessable. In1 generates each UUID using the browser's built-in cryptographically secure random number generator, the same source recommended for security-sensitive work, rather than a weak pseudo-random function that could produce predictable or repeating values. The result is a properly formed, standards-compliant version 4 UUID with the correct version and variant bits set, indistinguishable from one produced by a server library. Whether you need an identifier for a throwaway test, a database seed, a configuration file or a production system, you can trust that what comes out is both correctly formatted and genuinely random. And because the generation happens entirely on your own device, the values are never transmitted or logged anywhere before you use them.

Generate one or many at once

Sometimes you need a single identifier, and sometimes you need a whole column of them. In1 lets you set exactly how many UUIDs to generate, up to a sensible maximum, and produces the entire batch instantly. This is a real time-saver when you are seeding a database table, building test fixtures, creating a list of identifiers for a spreadsheet, or populating mock data for development. Instead of generating them one at a time and pasting each into place, you create the whole set in one step and copy it as a block, ready to drop wherever it needs to go. Each identifier in the batch is independently random, so there is no pattern or sequence linking them. Need more later? Generate another batch with a single click. The combination of bulk generation and instant copying turns what could be a tedious, repetitive task into something you finish in seconds, no matter how many identifiers the job calls for.

Format to match your system

Different systems expect UUIDs in slightly different shapes, so the tool gives you control over the format. The standard representation uses lowercase letters and four hyphens separating the five groups of digits, and that is the default because it is what most databases, languages and specifications use. But some contexts want the hyphens removed to save space or to fit a particular column, and some legacy systems or styles prefer uppercase hexadecimal. You can toggle hyphens on or off and switch between lower and upper case, and the whole batch updates to match. This means you do not have to run the output through a separate find-and-replace step to get the exact format your target expects — you choose it up front and copy a batch that is ready to use as-is. Small as these formatting options are, they remove a common source of friction when moving generated identifiers between tools that each have their own conventions. Picking the format once and copying a batch that already matches the destination is much faster than generating in the default shape and reformatting afterward, especially when you are producing dozens of identifiers at a time.

Private, instant and free

Identifiers might seem harmless, but the context around them — the names of unreleased projects, internal systems or test scenarios — often is not, and there is simply no reason to involve a server in generating a random value your own browser can produce. In1 creates every UUID locally using the browser's secure random generator. Nothing is uploaded, nothing is stored and there is no account or sign-up. Generation is instant because there is no network request, and it works exactly the same offline as online, so you can create identifiers on a plane or behind a corporate firewall without a hitch. There are no limits beyond a sensible per-batch maximum, and a single click copies the whole batch to your clipboard. It is a small, focused utility, but one that developers, testers and data engineers reach for constantly, and having it generate properly random, correctly formatted UUIDs privately and instantly is exactly what that everyday need calls for.

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