UUID (Universally Unique Identifier) is a 128-bit identifier standardized by RFC 4122. Version 4 UUIDs are randomly generated with 122 bits of randomness, making collisions virtually impossible.

UUID Generator - Generate Random UUID/GUID Online

Generate Single UUID

Format:

Bulk Generate

Count:

Click "Generate" to create UUIDs

Features

Cryptographically Secure

Uses crypto.randomUUID() with 122 bits of cryptographic randomness for maximum uniqueness.

Bulk Generation

Generate up to 1,000 UUIDs at once. Copy all or download as a TXT file.

Multiple Formats

Standard (with dashes), no dashes, UPPERCASE, or UPPERCASE without dashes.

One-Click Copy

Copy individual UUIDs or all generated UUIDs to clipboard with a single click.

Download as TXT

Export bulk-generated UUIDs as a plain text file, one UUID per line.

100% Private

All generation happens locally in your browser. No UUIDs are sent to any server.

How to Use

Choose Your Format

Select from standard (8-4-4-4-12 with dashes), no dashes, UPPERCASE, or UPPERCASE without dashes.

Generate a Single UUID

Click "Refresh" to generate a single UUID instantly. Click the clipboard icon to copy it.

Bulk Generate

Enter a count (1-1000) and click "Generate" to create multiple UUIDs at once.

Copy or Download

Use "Copy All" to copy all UUIDs to clipboard, or "Download TXT" to save them as a file.

UUID Version Comparison

Version	Generation Method	Sortable	Best For
UUID v1	Timestamp + MAC address	Partially	Legacy systems, audit trails
UUID v3	MD5 hash of namespace + name	No	Deterministic IDs from names
UUID v4	Cryptographic random (122 bits)	No	General purpose, most common
UUID v5	SHA-1 hash of namespace + name	No	Deterministic IDs (preferred over v3)
UUID v7	Unix timestamp + random	Yes	Database primary keys, time-ordered

This tool generates UUID v4 (random), the most widely used version for general-purpose unique identifiers.

Frequently Asked Questions

What is a UUID?

UUID (Universally Unique Identifier) is a 128-bit identifier standardized by RFC 4122, formatted as a 32-character hexadecimal string with hyphens: xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx. The M digit indicates the version (4 for random), and the N digit indicates the variant. UUIDs can be generated independently on any machine without coordination, yet collisions are virtually impossible.

What is the difference between UUID and GUID?

UUID and GUID (Globally Unique Identifier) refer to the same concept. GUID is the term used primarily in Microsoft technologies (.NET, SQL Server, COM), while UUID is the standard term used in RFC 4122 and most other platforms (Linux, macOS, PostgreSQL, Java, Python). The format and generation algorithms are identical.

Are UUID v4 values truly unique?

UUID v4 has 122 bits of randomness, yielding approximately 5.3 × 10^36 possible values. The probability of generating two identical UUIDs is astronomically small — you would need to generate 2.71 × 10^18 UUIDs to have a 50% chance of a single collision. For all practical purposes, they are unique.

Is crypto.randomUUID() secure enough for production use?

Yes. crypto.randomUUID() is part of the Web Crypto API and uses a cryptographically secure pseudo-random number generator (CSPRNG). The generated UUIDs are suitable for security-sensitive applications like session tokens, API keys, and database primary keys.

Should I use UUID v4 or UUID v7 for database primary keys?

UUID v7 is generally preferred for database primary keys because its time-ordered nature results in better B-tree index performance and natural chronological ordering. UUID v4 is still excellent for non-indexed use cases like API request IDs, correlation tokens, and session identifiers.

Are the generated UUIDs sent to a server?

No. All UUIDs are generated entirely in your browser using the Web Crypto API. No data is transmitted to any server. The generation is instant and private.

Related Tools

About UUID Generator

Generate random UUIDs (Universally Unique Identifiers) online free with FreeToolBox — create version 4 (random) UUIDs instantly for use as database primary keys, API request identifiers, session tokens, correlation IDs, and unique file names. UUIDs are 128-bit values defined by RFC 4122, formatted as 32 hexadecimal characters separated by hyphens (e.g., 550e8400-e29b-41d4-a716-446655440000). With 122 bits of cryptographic randomness in UUID v4, the probability of collision is approximately 1 in 5.3 × 10^36 — making them safe for independent generation across distributed systems without any central coordination.

This tool generates UUIDs using the browser's native crypto.randomUUID() API, which provides cryptographically secure pseudo-random numbers. Generate a single UUID with one click, or bulk-generate up to 1,000 UUIDs at once. Choose from four output formats: standard with dashes, without dashes, UPPERCASE, or UPPERCASE without dashes. Copy individual UUIDs, copy all at once, or download the list as a TXT file. All generation is local — no data leaves your browser. Completely free, instant, no account required.

Best use cases for UUID generation

Database and API identifiers – Generate IDs for records, requests, sessions, or jobs without needing a backend helper.
Bulk test data setup – Create many unique IDs at once for QA, fixtures, imports, or migration scripts.
Developer handoff workflows – Produce clean UUID formats for systems that require dashed, undashed, lowercase, or uppercase variants.
Private local generation – Make unique identifiers in the browser without calling an external generator or leaking project context.

When should you use UUID Generator vs other tools?

Use UUID Generator when you need collision-resistant identifiers, not human-memorable secrets. If you need random credentials instead, use Password Generator. If you need a deterministic digest of existing content, use Hash Generator.

No-upload workflow: IDs for internal datasets, testing, and app workflows stay local in your browser.

Frequently Asked Questions

When should I use UUIDs instead of auto-incrementing IDs?

UUIDs are useful when IDs must be generated independently across multiple systems, clients, or services without central coordination. Auto-incrementing IDs are shorter, but they are predictable and usually require a single authoritative database.