UUID / GUID Generator - Free Online Utility

Interactive UUID / GUID Generator

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How to Use UUID / GUID Generator

Select how many UUIDs you need (from 1 up to 100 in a batch).
Choose your formatting options (uppercase, lowercase, include hyphens, include braces).
Click "Generate UUIDs" to produce new random identifiers.
Click "Copy All" to transfer the list directly into your code or database migration script.

About & Key Features of UUID / GUID Generator

The UUID / GUID Generator produces cryptographically randomized Universally Unique Identifiers conformed to RFC 4122 Version 4 specifications. UUIDs are 128-bit numerical values formatted as 32 hexadecimal characters partitioned by hyphens (such as `de305d54-75b4-431b-adb2-eb6b9e546014`). In modern distributed systems and microservices architectures, UUIDs allow database clusters to generate globally unique primary keys without central coordinating servers.

Key Capabilities

Generates standard RFC 4122 Version 4 UUIDs using `crypto.getRandomValues`
Batch generation creating up to 100 UUIDs simultaneously with single-click bulk copying
Custom formatting toggles: uppercase/lowercase, with or without hyphens, wrapped in braces `{}`
Extremely low collision probability when UUID v4 values are generated correctly

Tips for Best Results

Use UUID v4 for primary keys in distributed databases like MongoDB, PostgreSQL, and DynamoDB to prevent ID conflicts during data migrations.
Choose lowercase with hyphens for standard REST API endpoints and web software.
Choose uppercase with braces (`{...}`) when configuring Windows COM or Microsoft GUID components.

Common Use Cases & Practical Applications

1. Database Primary Key Generation

Generate cryptographically unique RFC 4122 Version 4 UUIDs for distributed database records without central ID coordination.

Example: Generating `de305d54-75b4-431b-adb2-eb6b9e546014` to uniquely index a new transaction in a distributed PostgreSQL cluster.

2. Microservices Distributed Tracing & Request IDs

Create unique correlation IDs (`X-Request-ID`) to trace user transactions as they hop across microservice networks.

Example: Generating a unique trace GUID to monitor a checkout request from frontend API gateway to payment processor.

3. Test Fixtures and Mock Data Seeding

Generate batches of unique identifier strings for automated unit tests, seed scripts, and mock JSON API payloads.

Example: Generating 5 distinct UUIDs to seed mock user profiles in an automated Cypress test suite.

Frequently Asked Questions

What is the probability of two Version 4 UUIDs colliding?

The total number of possible UUID v4 values is $2^{122}$ (approximately $5.3 \times 10^{36}$). To put this in perspective: if you generated 1 billion UUIDs every second for 100 years, the probability of generating a single duplicate is less than 1 in a billion.

What are the 13th and 17th characters in a standard UUID v4 string?

In a valid UUID v4 (`xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx`), the 13th character is always `4` (indicating Version 4 random generation). The 17th character (`y`) is always one of `8`, `9`, `a`, or `b` (specifying the RFC 4122 variant bits).

What is the difference between a UUID and a GUID?

They refer to the exact same 128-bit identifier concept. UUID (Universally Unique Identifier) is the standard terminology adopted by the IETF and open-source world, while GUID (Globally Unique Identifier) is Microsoft's term.

Are these UUIDs generated using secure randomness?

Yes. They are generated using the browser's native Web Cryptography API (`crypto.getRandomValues`), ensuring high cryptographic entropy and unpredictability.

Are generated UUIDs stored in any database?

No. Identifiers are generated on-the-fly in browser memory and are discarded as soon as you leave or reload the page.