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DEVELOPER TOOLS

UUID Generator

Generate cryptographically secure (CSPRNG) UUID v4 values. Choose canonical, uppercase, compact without hyphens, or URN formats, and export batches as TXT, JSON, or JavaScript.

Tool statusRuns in your browser
Preview
prontouso://dev/uuid-v4
LocalWeb Crypto

Generate UUID v4

The most common case: one identifier ready to copy.

Options
Direct generation

No configuration is needed to generate a UUID v4. The button creates a new value using the browser's cryptographic API.

Representation

Changes only the copied/displayed text form. The 128 bits generated stay the same UUID.

The lowercase canonical form remains the default. "No hyphens" and URN are presentation options for integrating with specific systems.

● No history · no network

UUID ready

Click to copy, or generate another value.

Result
UUID V4Generated locally
Identifier
Canonical
UUID structure8–4–4–4–12
32 bits16 bitsVersion 4Variant48 bits
Version4 · random
VariantRFC · ?xxx
Size128 bits
SourceWeb Crypto

How it works

  1. Enter your input

    Fill in the values, paste your text, or upload the file this tool works with.

  2. See results instantly

    Most tools update live as you type; a few use a single button. Either way, the result appears right on this page.

  3. Use your results

    Copy, download, or share what the tool produces — you're always in control of the output.

Privacy and processing — Runs locally in your browser. This tool does not upload your input.

What is UUID Generator?

The UUID Generator creates universally unique identifiers (UUID v4 / GUID) with cryptographically secure randomness (CSPRNG), offering canonical, uppercase, compact, and URN formatting, plus bulk export to TXT and JSON.

UNDERSTAND THE TOOL

How to generate and structure UUID v4 and GUID identifiers

Learn how 128-bit UUID v4 values are structured, how cryptographic randomness guarantees uniqueness, and how to export identifiers in multiple formats.

Cryptographic generation and RFC 4122 standard

The tool uses cryptographically secure pseudo-random number generators (CSPRNG) native to the Web Crypto API (crypto.randomUUID() or crypto.getRandomValues()). This ensures 122 bits of true entropy within the 128-bit UUID, making duplicate collisions statistically impossible in production applications.

UUID v4 anatomy and bit layout

A UUID is displayed as 32 hexadecimal digits separated into 5 hyphenated groups in an 8-4-4-4-12 pattern (36 characters total). In version 4 UUIDs, the first digit of the third group is fixed to 4 (indicating the version), while the first digit of the fourth group is fixed to 8, 9, a, or b (defining the RFC 4122 / DCE 1.1 variant).

Representation formats (Uppercase, Compact, and URN)

You can switch between four textual representations of the exact same 128-bit identifier: canonical lowercase (standard), uppercase (common in Windows/GUID environments), compact (32 characters without hyphens for compact database keys and URLs), or URN (urn:uuid:...). Formatting changes only visual presentation and clipboard output.

Bulk generation and export formats

In batch mode, you can generate from 1 to 100 identifiers simultaneously using quick presets (5, 10, 25, 50, 100) or custom counts. Results can be copied or downloaded as plain text lines (.txt), a JSON array (.json), or a JavaScript array constant (.js).

Practical anatomy and formatting example

Representing UUIDs in canonical, compact, and URN formats

See how the same underlying UUID v4 value adapts across different language requirements and database schemas:

Canonical: f47ac10b-58cc-4372-a567-0e02b2c3d479\nCompact: f47ac10b58cc4372a5670e02b2c3d479\nURN: urn:uuid:f47ac10b-58cc-4372-a567-0e02b2c3d479

100% local and private generation

All UUIDs are generated directly within your browser's memory using the Web Crypto API. No generated identifiers are ever sent, logged, or stored on external servers.

Frequently Asked Questions

What is the difference between a UUID and a GUID?

UUID (Universally Unique Identifier) and GUID (Globally Unique Identifier) refer to the same 128-bit identifier standard; GUID is historically used in Microsoft environments, while UUID is the standard RFC 4122 term.

Is there any risk of two UUID v4 values colliding?

In practice, the probability of collision is negligible: with 122 bits of randomness, generating billions of UUIDs per second for decades would still yield a near-zero chance of duplication.

How does UUID v4 differ from other versions (v1, v3, v5, v7)?

UUID v4 is entirely random, whereas version 1 uses MAC address and timestamps, versions 3 and 5 use MD5/SHA-1 namespace hashes, and version 7 combines a millisecond sortable timestamp with random bits.

Can UUID v4 be used as a secret key or password?

No. While UUIDs are cryptographically random, they are intended as unique public identifiers, not as passwords, session secrets, or authentication tokens.

When should I use the compact (hyphenless) format?

The compact format removes all four hyphens, producing a 32-character hexadecimal string ideal for URL slugs, file paths, or storage engines that prefer delimiter-free keys.

Which export formats are supported for bulk generation?

You can copy or download batches as newline-separated plain text (TXT), a formatted JSON array, or a JavaScript array constant (.js).

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