UUID Generator

Generate universally unique identifiers (UUID v4) for your development needs. Create single or bulk UUIDs, format them as needed, and copy with a click. Secure, client-side, and no registration required.

Generate UUIDs without uploading anything

Cryptographically secure UUID v4 generation using the Web Crypto API — right in your browser. No uploads, no sign-up, no limits.

100% private

Instant generation

Free forever

How to use

1
Set Options
Choose the number of UUIDs you want to generate (1-100) and select your formatting options (uppercase, with/without hyphens, curly braces).
2
Click Generate
Click the 'Generate UUID(s)' button. The tool will instantly create the requested number of unique identifiers using crypto.randomUUID().
3
Copy Your UUIDs
Copy a single UUID by clicking its 'Copy' button, or copy the entire list to your clipboard by clicking 'Copy All'.

Fast, Secure, and Flexible UUID Generation

Generate cryptographically secure UUIDs with flexible formatting options.

Universally Unique

A 128-bit label used to uniquely identify information in computer systems without significant central coordination. 2^122 possible values.

Cryptographically Secure

Uses the browser's native crypto.randomUUID() function, backed by the OS CSPRNG. Suitable for session tokens and security-sensitive identifiers.

Flexible Formatting

Toggle between lowercase and uppercase, include or remove hyphens, and wrap in curly braces to match your system's expected format.

Bulk Generation

Generate up to 100 UUIDs in a single click. Copy them individually or all at once as a newline-separated list.

100% Private

All generation happens locally in your browser. Your UUIDs are never uploaded, stored, or logged.

Free with No Limits

No registration, no API key, no daily quotas. Free for personal and commercial use, forever.

Understanding UUIDs

What is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit identifier standardized by RFC 4122. It is represented as a string of 32 hexadecimal digits displayed in five groups separated by hyphens: 8-4-4-4-12, for a total of 36 characters. For example: '550e8400-e29b-41d4-a716-446655440000'. The '4' in the third group identifies the UUID version, and the first character of the fourth group identifies the variant.

UUIDs are designed to be globally unique without requiring a central coordinator. This means two independent systems can generate UUIDs simultaneously without any risk of collision, making them ideal for distributed databases, microservices, offline-first applications, and any system where a central ID authority is impractical.

UUID v4 vs. other versions

Version 4 (random): Uses random numbers for 122 of the 128 bits. This is the most commonly used version because it requires no coordination and is trivially easy to generate. Our tool generates v4 UUIDs using the browser's crypto.randomUUID() function.

Version 1 (time-based): Uses the current timestamp and the MAC address of the generating machine. This makes UUIDs sortable by creation time, but it leaks the MAC address, which is a privacy concern. Version 7 (time-ordered, proposed): Combines a Unix timestamp with random bits, producing UUIDs that are both unique and sortable — ideal for database primary keys.

When to use UUIDs vs. auto-increment IDs

Auto-increment integers (1, 2, 3, ...) are simple and compact, but they require a central authority to assign IDs and are not suitable for distributed systems. UUIDs can be generated independently by any node, are globally unique, and don't leak information about the number of records in your database. However, UUIDs are 16 bytes (vs. 4-8 bytes for integers), which increases storage and index size. For most modern applications, the benefits of UUIDs outweigh the storage cost.

Common Use Cases

Real-world scenarios where UUIDs are the right choice for unique identification.

Database Keys

Generate IDs on different servers or in offline apps without merge conflicts. Ideal for distributed databases and microservices.

Transaction IDs

Assign unique IDs to transactions, orders, and events for easy tracking, tracing, and debugging across services.

Session Tokens

Create unique, hard-to-guess tokens for user authentication, password reset links, and CSRF protection.

Asset Naming

Avoid file naming collisions in storage systems, CDN uploads, and user-generated content pipelines.

How does this compare to other UUID generators?

A side-by-side comparison of popular UUID generation tools.

Feature	NovaTools	UUIDGenerator.net	OnlineUUIDTools
Privacy (no upload)	100% local	Server-generated	Server-generated
Cryptographically secure	crypto.randomUUID()		Unknown
Bulk generation	Up to 100
Format options	Case, hyphens, braces		Limited
Works offline	After page load
Mobile friendly		Limited	Limited

Most online UUID generators generate UUIDs on their server, which means your UUIDs pass through their infrastructure. Our tool generates UUIDs locally using your browser's crypto API — they never leave your device.

FAQ

What is UUID version 4 (v4)?

UUID v4 is a version generated using random numbers. Of the 128 bits in a v4 UUID, 122 are randomly generated, while 6 bits are fixed to identify the version and variant. Due to the massive number of possible combinations (2^122), the probability of collision is infinitesimally small. The standard format is 8-4-4-4-12 hexadecimal digits, e.g., '550e8400-e29b-41d4-a716-446655440000'. The 4 in the third group identifies it as version 4.

Are these UUIDs truly unique?

Practically, yes. The number of possible v4 UUIDs is 2^122 (approximately 5.3 × 10^36), which is astronomically large. To put this in perspective, if you generated 1 billion UUIDs every second for 85 years, the probability of a single collision would still be less than 1 in 2 billion. In practice, UUID v4 collisions have never been observed in any real-world system. This is why UUIDs are trusted as primary keys in distributed databases, message IDs in event-driven systems, and file names in content-addressable storage.

Is this UUID generator secure?

Yes. This tool uses the built-in, cryptographically secure `crypto.randomUUID()` function available in modern web browsers (Chrome 92+, Firefox 95+, Safari 15.4+, Edge 92+). This function uses the operating system's CSPRNG (Cryptographically Secure Pseudo-Random Number Generator), which is the same source used for TLS key generation and other security-critical operations. The output is suitable for use as session tokens, API keys, and other security-sensitive identifiers.

What is the difference between UUID, GUID, and ULID?

UUID (Universally Unique Identifier) and GUID (Globally Unique Identifier) are essentially the same thing — GUID is Microsoft's name for the UUID standard defined in RFC 4122. Both are 128-bit identifiers. ULID (Universally Unique Lexicographically Sortable Identifier) is a newer format that combines a 48-bit timestamp with 80 bits of randomness, producing IDs that are sortable by creation time. UUIDs are not sortable. Our tool generates UUID v4, which is the most widely supported version.

Can I generate multiple UUIDs at once?

Yes. You can generate 1, 5, 10, 50, or 100 UUIDs in a single click. The tool generates each UUID independently using a separate call to crypto.randomUUID(), ensuring maximum entropy. For very large batches (1000+), the generation may take a few milliseconds but the browser will not freeze. All generated UUIDs are displayed in a text area where you can copy them individually or all at once.

What formatting options are available?

You can toggle between lowercase and uppercase hexadecimal digits, include or remove hyphens (dashes), and wrap the UUID in curly braces (e.g., {550e8400-e29b-41d4-a716-446655440000}). The default format is lowercase with hyphens, which is the standard RFC 4122 representation. Some systems (notably Microsoft .NET and some databases) use curly braces; others (like PostgreSQL UUID type) use the standard format without braces.

Is there a limit on how many UUIDs I can generate?

There is no artificial limit. The practical limit is your device's memory — each UUID is 36 characters (with hyphens), so generating 100,000 UUIDs produces about 3.6 MB of text, which is manageable. For generating millions of UUIDs, use a server-side tool or script instead of a browser tool.

Should I use UUIDs as database primary keys?

UUIDs are excellent for distributed systems where multiple nodes generate IDs independently without coordination. They prevent the collision problems of auto-increment integers. However, UUID v4 is random and not sortable, which can cause index fragmentation in databases like PostgreSQL and MySQL. For database primary keys, consider UUID v7 (time-ordered) or ULID, which combine randomness with sortability. UUID v4 is best for message IDs, request IDs, and other identifiers that don't need to be sorted.

Can I use this tool for commercial projects?

Yes. The tool is free for both personal and commercial use with no watermarks, no attribution required, and no usage limits. You retain full ownership of your generated UUIDs. There is no registration, no API key, and no subscription required.

Does the tool work on mobile devices?

Yes. The tool is fully responsive and works on iOS Safari and Android Chrome. The interface adapts to small screens with a vertical layout. The copy buttons are large and touch-friendly. UUID generation runs locally on your phone using the Web Crypto API, so it works even on slow network connections.

100% Client-Side & Private

This tool runs entirely in your browser using the Web Crypto API's crypto.

randomUUID() function.
We do not upload, store, or analyze any data.
All UUID generation happens locally — your generated UUIDs are never transmitted to any server, never stored in any database, and never logged.
This makes the tool suitable for generating session tokens, API keys, and other security-sensitive identifiers.

You can use it with complete confidence, even on air-gapped networks.

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