UUID/GUID Generator
Generate UUID v4 (random), v1 or v7 (timestamp-based) instantly, up to 100 at a time. Free, fast, no installation required, right in your browser. Perfect for developers.
100% local processing — nothing leaves your browser.Learn more
UUID Generator (v1, v4, v7): Create Unique Identifiers Instantly
Generate UUIDs (Universally Unique Identifiers) version 4, 1 or 7, up to 100 at a time, right in your browser. For version 4 (the default), this free tool uses the native cryptographic API crypto.randomUUID(): 122 random bits per identifier, for near-certain uniqueness. Versions 1 and 7 combine the generation time with random bits drawn from crypto.getRandomValues().
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
- Choose the version (random v4 by default, or timestamp-based v1 or v7) and the number of UUIDs (1 to 100)
- Click the "Generate UUID" button: the UUIDs are displayed instantly in standard format (8-4-4-4-12)
- Use the "Copy" button to copy one UUID, or "Copy All" for the whole list (one UUID per line)
- Click "Generate UUID" again to get new identifiers
- The random parts come from your browser's cryptographic random number generator
💡 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, with a negligible 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 non-sequential resource identifiers for your API endpoints: with UUID v4, nobody can walk through your resources by incrementing an ID (access control is still required).
POST /api/orders/a7b3c8d9-1234-4f5e-8abc-123456789def
🔐 Sessions & Tracing
Identify a session or a request (logs, analytics). Not for authentication tokens: RFC 9562 forbids using a UUID as a secret that grants access to a resource.
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 = `${crypto.randomUUID()}.pdf`;
🎫 Ticketing Systems
Create unique, non-sequential ticket numbers, order IDs, or customer references (v4) that don't reveal your business volume.
Ticket #f47ac10b-58cc-4372-a567-0e02b2c3d479
📊 Distributed Cache Systems
Generate unique cache keys for Redis, Memcached, or any multi-instance caching system.
redis.set(`cache:${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
UUID v4s come from crypto.randomUUID(), the native browser API (122 random bits, format compliant with RFC 9562). v1 and v7 draw their random bits from crypto.getRandomValues().
🕵️ 100% Private
No data sent to any server. Your UUIDs never leave your machine. Perfect for sensitive data.
♻️ Unlimited & Free
Generate 1 to 100 UUIDs per click, as many times as you need, 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: a copy button for each UUID and "Copy All" for a batch. 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-Mxxx-Nxxx-xxxxxxxxxxxx, where M is the version (1, 4 or 7 with this tool) and N the variant (8, 9, a or b).
Version 4 UUIDs (generated by default by this tool) are created randomly (only 6 bits are fixed) 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 variant defined by RFC 9562, which replaced RFC 4122 in May 2024. Versions 1 and 7 start with the generation time (readable by anyone), followed by random bits.
With 122 random bits, the probability that two given UUID v4s are identical is 1 in 5.3×10³⁶, and it remains 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 9562 (which replaced RFC 4122 in May 2024), 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! For v4, this tool uses crypto.randomUUID(), the native modern browser API, which produces UUID v4s compliant with RFC 9562 (same format as in the former RFC 4122). It's the same method used by professional libraries like uuid (npm) in browser mode.
The generated UUIDs are:
- ✅ RFC 9562 compliant (versions 1, 4 and 7)
- ✅ Generated with random bits from the browser's CSPRNG
- ✅ Compatible with all modern databases (PostgreSQL, MySQL, MongoDB, etc.)
- ✅ Usable as primary keys or resource identifiers, but not as session or authentication tokens (RFC 9562 forbids using them as secrets that grant access)
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 86 years to have a 50% chance of a collision
- Even after 1 trillion (10¹²) UUID v4s, the probability of a single collision is only about 1 in 10 trillion
- RFC 9562 points out, however, that a UUID is not a secret: it must never be used as an access token
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 + node ID (historically the MAC address). ⚠️ Reveals the generation time; this tool uses a random node, so no MAC address is exposed
- 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 (not offered by this tool)
- UUID v7: Standardized by RFC 9562 (2024), with a millisecond timestamp + random. Sortable by creation time, better for database indexes (but reveals the generation time)
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. For primary keys that sort by creation time, prefer v7.
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 with v4 (random order)
- Reduced readability for debugging
Solution: use UUID v7s, which sort by creation time (generated by this tool, or by uuidv7() since PostgreSQL 18), 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(); -- built in since PostgreSQL 13 (pgcrypto before)
SELECT uuidv7(); -- PostgreSQL 18+
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_orders_user_id ON orders(user_id); - Essential for joins and lookups on foreign keys (the primary key is already indexed automatically).
Never rely on UUID v4 ordering
UUID v4s are random. For chronological sorting, add a created_at column or use UUID v7s (sortable to the millisecond).
Always validate UUIDs server-side
Use a regex (versions 1, 4 and 7; add the i flag to accept uppercase): ^[0-9a-f]{8}-[0-9a-f]{4}-[147][0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$
📖 Resources & Documentation
📄 RFC 9562 - UUID Specification
Official document (May 2024, replaces RFC 4122) defining the UUID format and versions, including v7.
Read the RFC →🐘 PostgreSQL - UUID Type
Guide to using UUIDs in PostgreSQL with examples.
PostgreSQL Documentation →