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UUID/GUID Generator

Free online tool to generate UUID (Universally Unique Identifier) v4.

⚙️ 생성 옵션

✨ 생성된 UUID

UUID (Universally Unique Identifier) v4를 생성합니다. 각 UUID는 통계적으로 고유하며, 데이터베이스 키, 세션 ID 등으로 사용됩니다.

💡 예시

기본 (소문자, 하이픈):
550e8400-e29b-41d4-a716-446655440000
대문자:
550E8400-E29B-41D4-A716-446655440000
하이픈 없음:
550e8400e29b41d4a716446655440000

What is UUID?​

UUID (Universally Unique Identifier) or GUID (Globally Unique Identifier) is a 128-bit number used to uniquely identify information. UUID v4 is randomly generated, with collision probability nearly 0.

Key Features​

  • Bulk Generation: Choose 1, 5, 10, 20 items
  • Uppercase/Lowercase: Select desired format
  • Hyphen Option: Choose to include/remove hyphens
  • Instant Copy: Copy to clipboard with one click
  • Browser-based: No installation needed, runs entirely client-side

How to Use​

Basic Usage​

  1. Select number of UUIDs to generate (1, 5, 10, 20)
  2. Select options:
    • Uppercase: Check for uppercase generation
    • Include Hyphens: Check for hyphenated format
  3. Click "Generate" button
  4. Copy generated UUID for use

Format Selection​

Default Format (lowercase, with hyphens)​

550e8400-e29b-41d4-a716-446655440000

Uppercase​

550E8400-E29B-41D4-A716-446655440000

Without Hyphens​

550e8400e29b41d4a716446655440000

UUID Structure​

UUID v4 has the following structure:

xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx
  • x: Random hexadecimal (0-9, a-f)
  • 4: Version number (indicates v4)
  • y: Random hexadecimal (one of 8, 9, a, b)

Total 128 bits = represented as 32 hexadecimal digits.

Use Cases​

1. Database Primary Key​

CREATE TABLE users (
    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    name VARCHAR(100),
    email VARCHAR(100)
);

2. Distributed System ID​

Generate IDs independently on multiple servers without collision:

const userId = '550e8400-e29b-41d4-a716-446655440000';
const sessionId = 'a3bb189e-8bf9-3888-9912-ace4e6543002';

3. File Names​

const filename = `upload-${uuid}.jpg`;
// upload-550e8400-e29b-41d4-a716-446655440000.jpg

4. API Tokens​

Authorization: Bearer 550e8400-e29b-41d4-a716-446655440000

5. Session ID​

const sessionId = generateUUID();
sessionStorage.setItem('sessionId', sessionId);

UUID Versions​

UUID v1​

  • Timestamp + MAC address based
  • Time order guaranteed
  • MAC address exposure concern

UUID v4 (Used by this tool) ⭐​

  • Completely random
  • Most widely used
  • No privacy exposure

UUID v5​

  • Name-based (SHA-1 hash)
  • Same input → same UUID

Collision Probability​

UUID v4 collision probability is extremely low:

  • Total possible UUIDs: 2^122 ≈ 5.3 × 10^36
  • Collision probability with 1 billion generated: About 10^-18 (nearly 0)
  • All atoms in universe: 10^80

Practically no need to worry about collisions!

Programming Language Usage​

JavaScript​

// Browser
const uuid = crypto.randomUUID();

// Node.js
const { v4: uuidv4 } = require('uuid');
const uuid = uuidv4();

Python​

import uuid

# Generate UUID v4
my_uuid = uuid.uuid4()
print(my_uuid)  # 550e8400-e29b-41d4-a716-446655440000

Java​

import java.util.UUID;

UUID uuid = UUID.randomUUID();
String uuidString = uuid.toString();

C#​

using System;

Guid uuid = Guid.NewGuid();
string uuidString = uuid.ToString();

Frequently Asked Questions​

Q: Are UUIDs truly unique?​

Yes. Statistically, collision probability is nearly 0. Even generating 1 billion per second for the age of the universe, collision is virtually impossible.

Q: What's the difference between UUID v4 and v1?​

  • v1: Timestamp + MAC address based, time order guaranteed, privacy exposure concern
  • v4: Completely random, no time order, privacy safe

Q: Should I use uppercase or lowercase?​

Lowercase is generally standard, but both are valid. Choose based on system requirements.

Q: Are hyphens necessary?​

Hyphens are for readability. Some systems prefer format without hyphens.

Q: Can I use it as database primary key?​

Yes, possible. But for performance, consider sequential ID (AUTO_INCREMENT) or ULID.

Q: Can I use UUID as password?​

Not recommended. While UUID is unpredictable, using password hash functions (bcrypt, argon2) is safer.

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💬 Was this tool helpful?​

Feel free to send us your feedback or suggestions anytime!

Browser Compatibility​

This tool uses the Web Crypto API:

  • Chrome 92+ ✓
  • Firefox 95+ ✓
  • Safari 15.4+ ✓
  • Edge 92+ ✓

Privacy​

This tool operates entirely on the client side. Generated UUIDs are never sent to a server and are processed only in your browser.