Quick Answer

UUID Generator is a free online UUID v4 generator for developers by ThinkaBell. It runs UUIDs are generated locally in your browser using the Web Crypto API — no sign-up, no file uploads, and no data ever leaves your device.

Cryptographically secure: Uses crypto.getRandomValues() for true randomness from the OS entropy pool
Batch generation: Generate 1 to 100 UUIDs at once with multiple format options
Multiple formats: Uppercase, with or without hyphens, with or without braces
Privacy-first: no data collection, no tracking, no uploads.
Free forever: no premium tiers, no hidden charges, no accounts.

Free UUID Generator

Generate random UUID v4 values instantly. Batch generate up to 100 UUIDs with customizable format options — all in your browser.

UUIDs are the backbone of modern software development — used as database primary keys, session identifiers, API request IDs, and more. This generator creates cryptographically secure UUID v4 values using the Web Crypto API. Generate one or many, toggle uppercase and hyphens, wrap in braces for C-style macros, and copy or download the results. Nothing is stored, transmitted, or tracked.

Version

Quantity

Format Options

Uppercase Hyphens (with dashes) Braces ({uuid} format)

About UUID Generator

UUID Generator is a free web-based UUID v4 creation tool by ThinkaBell that runs 100% locally in your browser. No sign-up, no server uploads, no tracking — every UUID is generated on your device using the Web Crypto API, the same cryptographic random number generator that powers TLS certificates, banking applications, and enterprise security systems.

UUID stands for Universally Unique Identifier, and it is one of the most widely used identification standards in software development. A UUID is a 128-bit value represented as a 36-character string in the format xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx. The "4" in the 13th position identifies it as version 4 (randomly generated), and the "y" in the 17th position is restricted to 8, 9, a, or b to encode the UUID variant. This gives a theoretical collision probability of approximately 1 in 2^122 — a number so large that you would need to generate billions of UUIDs per second for decades before a single collision is statistically likely.

Developers use UUIDs as primary keys in databases, unique identifiers for API resources, session tokens, request trace IDs, distributed system node IDs, content identifiers, and virtually any scenario where a globally unique identifier is needed without coordinating with a central authority. Unlike sequential integers, UUIDs can be generated independently by any system at any time, making them ideal for distributed architectures, microservices, offline-capable applications, and client-side code that writes to a server later.

This generator lets you choose how many UUIDs to create at once — anywhere from 1 to 100. Toggle uppercase for case-insensitive identifiers, remove hyphens for compact storage, or wrap in curly braces for C/C++ macro and Go struct literal compatibility. Each generated UUID appears with its own copy button, and you can copy all UUIDs to the clipboard or download them as a plain text file. The entire process happens locally — no data ever leaves your browser.

Cryptographically secure randomness via Web Crypto API
Batch generate 1 to 100 UUIDs at once
Toggle uppercase, hyphens, and braces independently
Individual copy buttons for each UUID
Copy All to clipboard with one click
Download as plain text file (.txt)
Keyboard shortcuts for power users
Zero data collection — no cookies, no analytics, no server calls

Why This UUID Generator

Uses hardware-level entropy, not JavaScript Math.random()
Follows the RFC 4122 UUID v4 specification exactly
Works offline once the page loads
Mobile-friendly with large tap targets
Instant generation — no waiting or loading spinners
Copy and download options for easy integration
Free forever with no premium tiers or account walls

How to Use the UUID Generator

Generate cryptographically secure UUID v4 values in seconds. Follow these steps to create UUIDs in your preferred format.

Select the format options by toggling uppercase, hyphens, and braces. By default, UUIDs are generated in lowercase with hyphens (e.g., 550e8400-e29b-41d4-a716-446655440000). Toggle uppercase for identifiers that need case-insensitive matching, remove hyphens for compact storage, or add braces for C-style code.
Choose the quantity from the dropdown. Select 1 for a single UUID, or choose 5, 10, 25, 50, or 100 for batch generation. This is useful when you need multiple unique identifiers for database seeding, test data, or distributed systems.
Click the Generate button (or press Ctrl+Enter). The tool instantly creates the specified number of UUIDs using the Web Crypto API. Each UUID is cryptographically secure with a collision probability of approximately 1 in 2^122.
Copy individual UUIDs by clicking the copy button next to each one. Or click Copy All to put every generated UUID on your clipboard, one per line — ready to paste into SQL INSERT statements, JSON arrays, CSV files, or configuration files.
Download or clear when you are done. Click Download .txt to save all UUIDs as a plain text file. Click Clear to remove all results and start fresh with new settings.

Frequently Asked Questions

What is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit identifier used to uniquely identify information in computer systems. UUIDs are designed to be unique across both space and time, making them ideal for database keys, session identifiers, and any scenario where a truly unique ID is needed without coordinating with a central authority. They are represented as 36-character strings in the format xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.

What is UUID v4?

UUID v4 is the randomly generated version of UUIDs. It uses a cryptographically secure random number generator to create a 128-bit value. The version is indicated by the 13th character (always '4') and the variant is indicated by the 17th character (always one of 8, 9, a, or b). UUID v4 has an extremely low probability of collision — roughly 1 in 2^122. This is the most commonly used UUID version because it requires no central coordination or timestamp dependency.

Are UUIDs truly random?

UUID v4 values are generated using a cryptographically secure pseudo-random number generator (CSPRNG). This tool uses the Web Crypto API (crypto.getRandomValues), which draws entropy from the operating system's hardware random number generator. While technically pseudo-random, the output is computationally indistinguishable from true randomness and is safe for all practical purposes, including security-sensitive applications like session tokens and API keys.

Can I use UUIDs as primary keys?

Yes, UUIDs are commonly used as primary keys in databases, especially in distributed systems where multiple databases need to generate unique IDs independently. They avoid the sequential ID guessing vulnerability and prevent ID enumeration attacks. However, UUIDs are larger than integer IDs (36 bytes as strings vs 4 bytes for integers), which can impact index performance and storage costs. Many databases offer native UUID column types that optimize storage and indexing.

What's the difference between UUID versions?

UUID v1 uses a timestamp and MAC address (privacy concern due to exposed hardware address). UUID v2 is a DCE security variant with limited adoption. UUID v3 uses MD5 hashing of a namespace and name for deterministic generation. UUID v4 is purely random — the most widely used version. UUID v5 uses SHA-1 hashing of a namespace and name, offering better security than v3. UUID v7 uses a Unix timestamp prefix for time-ordered generation, which is gaining popularity for database keys due to better index locality.

Key Terms

UUID: Universally Unique Identifier — a 128-bit value used to uniquely identify information across computer systems without central coordination.
UUID v4: The randomly generated version of UUIDs, using a cryptographically secure random number generator. Most commonly used due to simplicity and privacy.
CSPRNG: Cryptographically Secure Pseudo-Random Number Generator — a random number generator that meets cryptographic standards for unpredictability and resistance to prediction attacks.
Collision: A situation where two independently generated UUIDs produce the same value. For UUID v4, the probability is approximately 1 in 2^122, making collisions practically impossible.
Web Crypto API: A browser-native JavaScript API that provides access to cryptographic functions including secure random number generation via crypto.getRandomValues().
RFC 4122: The Internet standard that defines the UUID format, including versioning, variant bits, and the canonical string representation used worldwide.