UUID/GUID Generator
Generate random, secure UUID v4 (Universally Unique Identifiers) instantly. Free, fast, and no installation required. Perfect for developers.
UUID v4 Generator: Create Unique Identifiers Instantly
Generate UUIDs (Universally Unique Identifiers) version 4 securely and instantly, right in your browser. This free and unlimited tool uses the native cryptographic API crypto.randomUUID() to guarantee maximum entropy and near-certain uniqueness for every generated identifier.
Whether you're a backend developer looking for primary keys for your databases, a frontend developer managing session identifiers, or a system architect designing distributed APIs, this UUID generator meets all your unique identification needs without central coordination.
How to Use
- Click the "Generate" button to create a new UUID v4
- The UUID is displayed instantly in standard format (8-4-4-4-12)
- Use the copy button to copy the UUID to clipboard
- Click "Generate" again to get a new unique identifier
- Each generated UUID is cryptographically secure and unique
💡 Why Does This UUID Generator Exist?
In modern distributed application development, reliably generating unique identifiers is a constant challenge. Traditional solutions like database auto-increments create bottlenecks and synchronization issues in distributed architectures.
UUIDs solve this problem by allowing any system to generate unique identifiers independently, without risk of collision. This generator saves you from installing libraries, writing code, or depending on third-party services.
🎯 Typical Use Case:
You're developing a REST API and need to create identifiers for new resources. Instead of waiting for database insertion to get an auto-incremented ID, you generate a UUID client-side, enabling asynchronous processing and a better user experience.
🔧 Practical Use Cases
🗄️ Distributed Databases
Use UUIDs as primary keys in PostgreSQL, MongoDB, or DynamoDB to avoid conflicts during multi-master replications.
CREATE TABLE users (id UUID PRIMARY KEY DEFAULT gen_random_uuid(), ...);
🌐 RESTful APIs
Create predictable and secure resource identifiers for your API endpoints, avoiding sequential ID enumeration attacks.
POST /api/orders/a7b3c8d9-1234-4f5e-8abc-123456789def
🔐 Sessions & Authentication
Generate unguessable session tokens, increasing security for your web and mobile applications.
sessionStorage.setItem('session_id', crypto.randomUUID());
📁 Unique File Names
Avoid name collisions when uploading files to S3, Azure Blob, or any cloud storage system.
const filename = `${crypto.randomUUID()}.pdf`;
🎫 Ticketing Systems
Create ticket numbers, order IDs, or customer references that are impossible to guess or forge.
Ticket #f47ac10b-58cc-4372-a567-0e02b2c3d479
📊 Distributed Cache Systems
Generate unique cache keys for Redis, Memcached, or any multi-instance caching system.
redis.set(`cache:${uuid}`, data, 'EX', 3600);
✨ Why Use This Generator Over Others?
🚀 Instant & Local
Generation in less than 1ms directly in your browser. No server calls, no network latency.
🔒 Cryptographically Secure
Uses crypto.randomUUID(), the native browser API compliant with RFC 4122 with 122 bits of entropy.
🕵️ 100% Private
No data sent to any server. Your UUIDs never leave your machine. Perfect for sensitive data.
♻️ Unlimited & Free
Generate 1, 10, or 10,000 UUIDs without limits, no signup, no ads. Always free.
📱 Cross-Platform
Works on all modern browsers: Chrome, Firefox, Safari, Edge. Desktop and mobile.
📋 One-Click Copy
Intuitive interface with automatic copy button. Save time in your development workflow.
❓ Frequently Asked Questions (FAQ)
What is a UUID and how does it work?
A UUID (Universally Unique Identifier) is a 128-bit (16-byte) identifier represented as 32 hexadecimal characters separated by hyphens: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx.
Version 4 UUIDs (which this tool generates) are created entirely randomly using a cryptographically secure pseudo-random number generator. Bits 4-7 of the 7th byte indicate the version (4), and bits 6-7 of the 9th byte indicate the RFC 4122 variant.
With 122 bits of entropy, the probability of collision is 1 in 5.3×10³⁶, essentially zero even when generating billions of UUIDs.
What's the difference between UUID and GUID?
UUID and GUID are the same thing, just different terms used by different ecosystems:
- UUID (Universally Unique Identifier): Standard term defined by RFC 4122, used in Unix/Linux and web standards
- GUID (Globally Unique Identifier): Term used by Microsoft in Windows and .NET ecosystem
Both refer to the same 128-bit format. Our generator produces identifiers compatible with both terminologies.
Can I use the generated UUIDs in production?
Yes, absolutely! This tool uses crypto.randomUUID(), the native modern browser API that implements the RFC 4122 specification for UUID v4. It's the same method used by professional libraries like uuid (npm) in browser mode.
The generated UUIDs are:
- ✅ RFC 4122 compliant
- ✅ Cryptographically secure (uses the browser's CSPRNG)
- ✅ Compatible with all modern databases (PostgreSQL, MySQL, MongoDB, etc.)
- ✅ Usable as primary keys, tokens, session identifiers
What is the risk of collision (two identical UUIDs)?
The risk of collision between two UUID v4s is astronomically low. With 122 bits of entropy (after excluding version and variant bits), there are approximately 5.3×10³⁶ possible combinations.
To put this in perspective:
- Generating 1 billion UUIDs per second, it would take about 85 years to have a 50% chance of a collision
- It's safer than being struck by lightning 80 times in a row
- The NSA recommends using UUIDs for non-secret identifiers
In practice, the collision risk is negligible for any realistic application.
Why choose UUID v4 over v1, v5, or v7?
Each UUID version has its advantages:
- UUID v1: Based on timestamp + MAC address. ⚠️ Exposes your machine's MAC address and generation time (privacy concern)
- UUID v4: Entirely random. ✅ No information revealed, maximum security and privacy
- UUID v5: Based on SHA-1 hash of a namespace + name. Useful for generating deterministic UUIDs
- UUID v7: New standard (2024) with timestamp + random. Better for database indexes
UUID v4 is recommended when you want unpredictable identifiers without revealing any information about the system or generation time. It's the default choice for most applications.
Are UUIDs suitable as database primary keys?
Yes, but with some considerations:
✅ Advantages:
- Decentralized generation (no need to coordinate with DB)
- Easier database merging (no ID conflicts)
- Increased security (impossible to guess next ID)
- Compatibility with distributed architectures and microservices
⚠️ Disadvantages:
- Size: 16 bytes vs 4-8 for INT/BIGINT (index impact)
- Insertion performance: worse for B-tree indexes (random order)
- Reduced readability for debugging
Solution: PostgreSQL offers UUID v7 or use UUIDs as external identifiers + auto-increment internally.
Does this tool work offline?
Yes! Once the page is loaded, the tool works entirely offline. JavaScript runs locally in your browser and requires no internet connection to generate UUIDs.
You can even bookmark this page or open it from your browser cache. Perfect for working on the go or in environments without internet.
How do I integrate UUID generation into my code?
JavaScript (modern browser):
const uuid = crypto.randomUUID(); // Native, no dependencies
Node.js (v14.17+):
const { randomUUID } = require('crypto');
const uuid = randomUUID();
Python:
import uuid
my_uuid = str(uuid.uuid4())
PostgreSQL:
SELECT gen_random_uuid(); -- pgcrypto extension required
Java:
String uuid = UUID.randomUUID().toString();
📚 Best Practices for Using UUIDs
Use UUIDs for publicly exposed identifiers
URLs like /users/123 allow enumeration. Prefer /users/a7b3c8d9-...
Store UUIDs in binary format (16 bytes) in databases
PostgreSQL: UUID, MySQL: BINARY(16). Convert to/from string on the application side.
Use indexes on UUID columns for performance
CREATE INDEX idx_user_id ON users(id); - Essential for joins and lookups.
Never rely on UUID ordering
UUID v4s are random. For chronological sorting, add a created_at column.
Always validate UUIDs server-side
Use a regex: ^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$
📖 Resources & Documentation
📄 RFC 4122 - UUID Specification
Official document defining the UUID format and generation algorithm.
Read the RFC →🐘 PostgreSQL - UUID Type
Guide to using UUIDs in PostgreSQL with examples.
PostgreSQL Documentation →