UUID Generator

Create random UUID/GUID values in batches.

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// about

About this Tool

UUID (or GUID) is a unique 36-character ID made of random numbers and letters. It helps name files, database records, or accounts so two items never get confused.

How to use it

  1. Choose how many UUIDs you need (1 to 100).
  2. Select uppercase or lowercase formatting.
  3. Click 'Generate' and copy your brand new IDs.

Why people use this tool

  • Generates guaranteed unique IDs that will never overlap with anyone else.
  • Create up to 100 unique IDs at once with a single click.
  • Option to choose uppercase or lowercase letters depending on your project needs.

Frequently Asked Questions

What does a UUID look like?

It looks like a long string separated by hyphens, such as 123e4567-e89b-12d3-a456-426614174000.

Can two generated UUIDs ever be the same?

Mathematically, the chance of generating identical UUIDs is practically zero.

Which UUID version is created here?

This tool creates Version 4 UUIDs, which are built using random numbers.

Guides · Data · 6 min read

UUID Guide: v4 vs v7 and Using UUIDs as Database Primary Keys

Strings like 550e8400-e29b-41d4-a716-446655440000 identify orders, files and API requests everywhere. Learn how UUIDs are generated and which version to choose.

A UUID (Universally Unique Identifier) is a 128-bit identifier that lets anyone create IDs that will not clash, without asking a central server. Microsoft calls it a GUID. The current standard is RFC 9562, published in 2024.

UUID structure, how versions differ, why collisions are practically impossible, and why UUID v7 is overtaking v4 for database primary keys.
Read guide →
Build it with AI

Build this tool yourself with AI

Want your own version of this tool? Copy the work-order prompt into an AI chat, or save the skill file for an AI coding agent. Both describe the features, edge cases and test cases we used when building it.

AI work-order prompt

Paste it as-is into an AI chat such as Claude, ChatGPT or Gemini.

You are an experienced full-stack web developer. Build a web tool called "UUID Generator" that meets the requirements below.

## Goal

Build a generator for UUID v4 (random) and v7 (time-ordered).

## Core features

- Choose version v4 or v7
- Generate 1 to 1,000 at once
- Upper/lower case and with/without hyphens
- Output as lines, comma-separated or a JSON array
- Copy all

## Inputs

- Version, count, format options

## Outputs

- List of UUIDs
- Text in the chosen format

## Edge cases and handling rules

- Keep v7 values sortable even within the same millisecond
- Prevent counts above the limit
- Fallback for browsers without crypto.randomUUID
- Set version and variant bits according to RFC 9562

## Implementation requirements

- Build it as a single page (HTML, CSS, JavaScript) that runs entirely in the browser, and never send the user's input to a server.
- Make the UI responsive and easy to use on mobile; label every input and keep everything keyboard accessible.
- Add a Copy button for results and show clear, friendly error messages for invalid input.
- Keep the core logic in functions separate from the UI so it can be unit-tested.

## Definition of done (test cases)

- The third group of a v4 UUID starts with '4'
- Several v7 values sort in creation order
- Removing hyphens yields 32 characters

First outline your implementation plan in at most five lines, then write the complete code, and finally explain how to check the test cases above.

Skill (SKILL.md)

Save it as .claude/skills/build-uuid-generator/SKILL.md for AI coding agents such as Claude Code to reuse whenever you build or change this tool.

---
name: build-uuid-generator
description: Use when building or changing a UUID Generator tool. Build a generator for UUID v4 (random) and v7 (time-ordered).
---

# Build: UUID Generator

## Goal

Build a generator for UUID v4 (random) and v7 (time-ordered).

## Workflow

1. Review the required features, inputs and outputs below and ask about anything missing first.
2. Implement the core logic as pure functions separate from the UI.
3. Check the logic against the test cases in the verification list.
4. Build a responsive UI with an input form, a result area and a Copy button.
5. Reproduce each edge case listed under Rules and refine the error messages.

## Core features

- Choose version v4 or v7
- Generate 1 to 1,000 at once
- Upper/lower case and with/without hyphens
- Output as lines, comma-separated or a JSON array
- Copy all

## Inputs

- Version, count, format options

## Outputs

- List of UUIDs
- Text in the chosen format

## Rules

- Keep v7 values sortable even within the same millisecond
- Prevent counts above the limit
- Fallback for browsers without crypto.randomUUID
- Set version and variant bits according to RFC 9562
- Build it as a single page (HTML, CSS, JavaScript) that runs entirely in the browser, and never send the user's input to a server.

## Verification

- [ ] The third group of a v4 UUID starts with '4'
- [ ] Several v7 values sort in creation order
- [ ] Removing hyphens yields 32 characters

Tips for working with AI

  • Tell the AI your stack (for example React, Vue or plain HTML) on the first line so the code matches your project.
  • Ask it to run the listed test cases and show the results before you accept the code.
  • Never paste real secrets, customer data or API keys into the prompt; use sample values instead.