Online UUID / GUID generator

Generate RFC 4122 version-4 UUIDs (GUIDs)—pick count and format, then click Generate. Click the output to copy one or many IDs.

About online UUID and GUID generation

APIs, databases, and test fixtures often need opaque unique IDs. This page generates RFC 4122 version-4 UUIDs using crypto.getRandomValues in your browser session—click Generate after you set count and format.

GUID is Microsoft’s name for the same 128-bit identifier shape (8-4-4-4-12 hex groups). Output can be lowercase, UPPERCASE, wrapped in braces, or prefixed as urn:uuid: for legacy .NET or URN fields.

Online UUID / GUID generator capabilities

Version 4 (random)

Each ID uses 122 random bits with version nibble 4 and RFC variant bits—suitable for primary keys, correlation IDs, and mock JSON when you do not need time-sortable IDs (use ULID elsewhere for that).

Batch copy

  1. Set Count from 1 to 100, choose a format chip, then click Generate.
  2. One UUID appears on a single line; multiple IDs are newline-separated for pasting into CSV or SQL IN lists.
  3. Click the output area to copy the full block—same click-to-copy pattern as other converters on this site.

Format options

  1. Lowercase — typical for PostgreSQL uuid columns and JSON APIs.
  2. UPPERCASE — common in Windows registry and some enterprise docs.
  3. {braces} — curly-brace form used by COM and older GUID examples.
  4. urn:uuid: — URN syntax when a spec asks for a namespaced string, not bare hex.

When not to use random UUIDs

  • Secrets or session tokens need dedicated generators with entropy and rotation policies—not display UUIDs.
  • Public sequential IDs may be preferable when you want short URLs or natural sorting by creation time.
  • Collision risk for v4 is negligible at application scale; still use DB unique constraints in production.

Common use cases

OpenAPI and mock JSON

Drop fresh id fields into Swagger examples or Postman bodies without installing uuid CLI—generate ten at once for list endpoints.

Database seed scripts

Paste newline-separated UUIDs into INSERT fixtures for PostgreSQL, MySQL CHAR(36), or SQL Server uniqueidentifier tests.

.NET GUID strings

Switch to braces or uppercase when your C# sample or appsettings expects {XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}.

Frequently asked questions

How do I generate a UUID online?
Open this page, set how many IDs you need (1–100), pick lowercase, uppercase, braces, or urn format, and click Generate. Click the output to copy.
What is the difference between UUID and GUID?
Same 128-bit layout and string formatting—GUID is the usual term on Windows/.NET; UUID is the IETF/RFC name. This tool outputs standard RFC 4122 version-4 values.
Are these UUIDs cryptographically random?
Version 4 IDs here use the browser CSPRNG via crypto.getRandomValues. They are fine for resource identifiers; do not reuse them as long-term secrets without a proper key-management design.
Can I generate multiple UUIDs at once?
Yes—set Count up to 100. Each line is one UUID ready for bulk paste into spreadsheets, SQL, or JSON arrays you assemble manually.
Why version 4 only?
v4 is what most “uuid generator online” searches expect—pure random IDs. Time-based v1 or draft v7 are different products; this page stays focused on the common API/database case.
Do I need hyphens in the string?
Canonical UUID text includes hyphens at fixed positions. Some systems accept 32 hex digits without hyphens—this generator keeps the standard dashed form unless you choose urn or braces wrapping.

Format examples

  • Lowercase v4550e8400-e29b-41d4-a716-446655440000 — typical JSON id
  • UPPERCASE550E8400-E29B-41D4-A716-446655440000 — registry-style docs
  • {braces}{550e8400-e29b-41d4-a716-446655440000} — COM / legacy GUID samples
  • urn:uuid:urn:uuid:550e8400-e29b-41d4-a716-446655440000 — URN field syntax