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Online UUID Generator v4

Generate random UUID v4 values (RFC 4122) locally in your browser—no network calls. Create one or many, pick output format, and copy in one click.

Category: Developer · URL: /tools/online-uuid-generator-v4.html
Generate 1–500 UUIDs at once.
Version 4 + RFC 4122 variant.
Tip: one UUID per line. This tool runs locally; it does not send data anywhere.
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Privacy: runs locally in your browser. No uploads, no tracking scripts.

How to use

Use the generator to create RFC 4122 UUID v4 strings in the format your app expects.

  1. Set how many UUIDs you want (1–500).
  2. Choose an output format (standard, no hyphens, braces, or URN).
  3. Optionally enable uppercase output.
  4. Click Generate, then Copy to copy all results.
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Secondary intents covered: Generate one or many UUID v4 values for testing or data seeding, Output UUIDs in different formats (standard, compact, braces, URN), Copy generated UUIDs to clipboard quickly, Ensure UUIDs look valid (version 4 + RFC 4122 variant), Create IDs for database primary keys or object identifiers, Generate uppercase UUIDs for systems that require it, Reset the tool back to safe defaults

FAQ

What is a UUID v4?

A UUID v4 is a 128-bit identifier generated from random data, formatted per RFC 4122 (e.g., xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx).

Is this UUID generator truly random?

When “Use crypto” is enabled, it uses crypto.getRandomValues for strong randomness; otherwise it falls back to Math.random, which is weaker.

Does this tool send anything to a server?

No. Generation happens locally in your browser with no network requests.

What formats can I output?

Standard (hyphenated), compact (no hyphens), braces ({uuid}), and URN (urn:uuid:uuid).

Can UUIDs collide?

In practice, collisions for properly generated v4 UUIDs are extremely unlikely, but no scheme can guarantee “never” across all time and systems.

Are UUID v4 values safe for database primary keys?

Often yes, but consider index/fragmentation tradeoffs; some databases perform better with time-ordered IDs (e.g., UUIDv7/ULID).

How do I validate a UUID v4?

Use a regex that checks version 4 and the RFC 4122 variant, such as: ^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$.