UUID Generator

Generate UUID v4 identifiers using crypto.randomUUID.
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UUID v4

Cryptographically random via crypto.randomUUID().

Bulk Generate

Generate up to 100 UUIDs at once.

Copy Result

One-click copy to clipboard.

Client-side

All processing in your browser. No data uploaded.

About UUID Generator

A UUID (Universally Unique Identifier) is a 128-bit label used to uniquely identify objects in computer systems. Version 4 UUIDs are generated using cryptographically random numbers, making them statistically unique without any central coordination. They are formatted as 32 hexadecimal digits displayed in five groups separated by hyphens: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx. UUIDs are widely used in distributed systems, databases, and APIs as primary keys, session tokens, and request correlation IDs — anywhere you need a globally unique value that can be generated independently on any machine without risk of collision. This tool generates one or up to 100 UUIDs at once using the browser's built-in crypto.randomUUID() API, which guarantees cryptographic-quality randomness. You can toggle uppercase output and copy individual UUIDs or the entire batch with a single click. All generation happens entirely in your browser — nothing is sent to any server, so your identifiers remain private.

How to Use UUID Generator

  1. Choose how many UUIDs to generate (1–100) using the Count input.
  2. Optionally check the Uppercase toggle if you need capital letters in the output.
  3. Click Generate to create a fresh batch of cryptographically random UUID v4s.
  4. Click Copy next to any individual UUID to copy just that one to your clipboard.
  5. Click Copy All to copy the entire batch as newline-separated values.
  6. Paste the UUIDs into your database, code, or configuration as needed.

Frequently Asked Questions

Is UUID v4 truly unique?

UUID v4 uses 122 bits of randomness. The probability of generating a duplicate is so small (about 1 in 5.3×10³⁶) that for all practical purposes they are guaranteed unique, even if you generate billions of them.

What is the difference between UUID v1 and v4?

UUID v1 is based on the current timestamp and your machine's MAC address, which can leak information and may have collisions if generated quickly. UUID v4 is purely random, making it safer for most applications.

Can I use UUIDs as database primary keys?

Yes. UUIDs make excellent primary keys in distributed systems because they can be generated client-side without a round-trip to the database. The trade-off is that they are larger than integer keys and slightly slower to index.

Does this tool store the UUIDs it generates?

No. All generation happens locally in your browser using the Web Crypto API. No UUIDs or any other data are sent to our servers.

What format does UUID v4 use?

UUID v4 follows the RFC 4122 format: 8-4-4-4-12 hexadecimal characters separated by hyphens, totalling 36 characters including hyphens (32 hex digits).

Free UUID / GUID v4 Generator: Bulk Generate Cryptographically Secure Identifiers

Generate standard RFC 4122 version-4 universally unique identifiers individually or in bulk

The Challenge & The Solution

Distributed systems and databases require collision-resistant unique primary keys and transaction IDs without relying on centralized counters.

Metoolzy UUID Generator produces cryptographically secure UUID/GUID v4 identifiers using browser crypto.getRandomValues() with bulk generation up to 500 IDs.

Key Features of UUID Generator

  • RFC 4122 v4 Compliance: Guaranteed cryptographic randomness using CSPRNG.
  • Bulk Generation: Generate up to 500 unique IDs simultaneously.
  • Format Customization: Toggle hyphens, uppercase/lowercase, and curly braces.
  • One-Click Copy: Copy single or bulk identifiers instantly.

Step-by-Step Guide

  1. Select the quantity of UUIDs needed.
  2. Configure uppercase/hyphen formatting.
  3. Click Generate and Copy to clipboard.

Feature Comparison

UUID Version Generation Mechanism Best For
UUID v1 Timestamp & MAC address Legacy distributed ordering
UUID v4 Pure cryptographic randomness Modern database primary keys & API IDs
UUID v5 Namespace + SHA-1 hashing Deterministic ID generation

Practical Real-World Use Cases

  • Database primary keys (PostgreSQL, SQLite, Mongo)
  • Unique request tracking IDs in microservices
  • Test fixture generation for QA testing

Frequently Asked Questions (FAQ)

What is the probability of a UUID v4 collision?

The probability is astronomically low—generating 1 billion UUIDs per second for 100 years would still yield less than a 50% chance of a single collision.