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UUID Generator

Generate and validate unique UUIDs and GUIDs instantly. Supports v4 (random), v7 (time-ordered), v1 (timestamp) and Nil UUID. Everything runs in your browser.

UUID Checker

Paste any UUID or GUID to validate it, identify the version, and read the embedded timestamp (for v1 and v7).

Validation runs in your browser. Nothing is sent to a server.

What is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit number that uniquely identifies a resource inside a system. Microsoft calls the same value a GUID, but the format and guarantees are identical. It is written as 32 hexadecimal digits in five groups separated by hyphens — 8-4-4-4-12 — for example, 550e8400-e29b-41d4-a716-446655440000. The goal is to let any system, at any time, generate an identifier with virtually zero collision probability without coordinating with a central server.

UUIDs show up everywhere: database primary keys, transaction IDs, session tokens, file identifiers, message IDs, object keys in queues, and much more. Whenever you see a string like "f47ac10b-58cc-4372-a567-0e02b2c3d479" in an API or URL, it is almost always a UUID.

How our UUID Generator works

This UUID generator is 100% client-side. When you click Generate, your browser calls the Web Crypto API — the same cryptographic random number generator used by HTTPS and password managers — to produce the identifier bits. There are no network calls, nothing is logged, and you do not need to create an account. That means you can safely use the output as a production database seed, session token, or invite code.

The default interface stays minimal: pick a version and click Generate. If you need more control — batches up to 1,000 UUIDs, uppercase, no hyphens, CSV, braces or quotes — open the Advanced settings panel right below the Generate button.

What is a UUID Checker (Validator)?

A UUID Checker — sometimes called a UUID validator or UUID decoder — is a tool that takes a string and answers three questions: is it a valid UUID, which version is it, and (when the version embeds a timestamp like v1 or v7) when was it generated? It is the fastest way to confirm whether an identifier from a log, database, or API response is well-formed before you spend time debugging something deeper.

Our UUID Checker is format-tolerant: it accepts UUIDs with or without hyphens, in upper or lower case, wrapped in braces {…} or quotes "…", and always returns the canonical lowercase, hyphenated form. For UUID v1 and v7 it automatically decodes the embedded timestamp to UTC — useful for auditing, debugging, and data forensics.

UUID Versions Explained

There are several UUID versions defined by RFC 4122 and the modern update RFC 9562. Each one encodes the 128 bits differently and is designed for a different use case.

UUID v1 — time and node based

UUID v1 combines a 60-bit timestamp with a 48-bit node identifier (historically the machine’s MAC address). It allows rough time ordering but can leak information about when and where it was created. It is considered legacy today — if you need time ordering, use v7 instead.

UUID v3 / v5 — name based

v3 (MD5) and v5 (SHA-1) always produce the same UUID from a namespace plus a name. They are useful when you need a deterministic identifier — for example, the same UUID for a URL or email — without storing a mapping. This tool does not generate v3/v5 directly because they require a namespace, but the Checker correctly identifies them.

UUID v4 — random

UUID v4 is 122 random bits plus 6 fixed bits for version and variant. It is the most widely used version in the world: simple, supported everywhere, and unpredictable. It is the default choice when you simply need a unique identifier with no metadata.

UUID v7 — time-ordered (modern)

UUID v7 (RFC 9562, 2024) starts with a 48-bit Unix millisecond timestamp followed by random bits. It gives you the best of both worlds: random but monotonically increasing identifiers. For primary keys in modern databases (Postgres, MySQL, MongoDB) v7 outperforms v4 because it keeps B-tree indexes compact and reduces insert fragmentation.

UUID vs GUID

GUID and UUID are the same 128-bit identifier with two different names. "GUID" (Globally Unique Identifier) is the term Microsoft popularized with COM, .NET, and SQL Server; "UUID" (Universally Unique Identifier) is the IETF term from RFC 4122 and RFC 9562. Any UUID generated on this page can be pasted into a SQL Server GUID field, a uniqueidentifier property, or an Active Directory attribute without conversion.

When to use UUIDs

Database primary keys

UUID v7 makes a great primary key — its time-ordered prefix keeps inserts fast while still avoiding the predictability of auto-increment IDs.

API request IDs

Generate a v4 UUID per request and include it in your logs to trace a single call across microservices and queues without coordination.

Session and user tokens

A v4 UUID is unpredictable enough to use as a one-time session ID, password-reset token, or invite code without a database lookup.

Test fixtures and seed data

Bulk-generate hundreds of UUIDs at once to seed staging databases, write integration tests, or pre-allocate IDs for offline-first apps.

Frequently Asked Questions

A UUID (Universally Unique Identifier) — also called a GUID (Globally Unique Identifier) on Microsoft platforms — is a 128-bit value used to uniquely identify information in computer systems. UUIDs are written as 32 hexadecimal characters split into five groups separated by hyphens, like 550e8400-e29b-41d4-a716-446655440000. Because they are generated from random or time-based sources, the chance of a collision is so low that they can be created independently without any central authority.
Our UUID generator runs entirely in your browser using the secure Web Crypto API. Nothing is sent to a server — every UUID you create stays on your device. Choose the version (v4, v1, v7 or Nil), pick how many you need, and click Generate. Open Advanced settings if you want to switch case, remove hyphens, or wrap each UUID in braces, quotes or CSV.
UUID v4 is generated entirely from random bits, which makes it perfect when you simply need a unique value with no ordering. UUID v7 (defined in RFC 9562) starts with a 48-bit Unix timestamp in milliseconds, so newer UUIDs sort after older ones. v7 is the modern choice for database primary keys because it improves index locality and write performance compared to v4.
Use v4 by default — it is the most widely supported, easiest to generate, and unpredictable. UUID v1 encodes a timestamp and a node ID (historically a MAC address), which can leak information about when and where the UUID was generated. If you need time-ordering for database performance, prefer v7 over v1.
Yes. GUID is the name Microsoft uses for the same 128-bit identifier defined as a UUID in RFC 4122 / RFC 9562. The format and uniqueness guarantees are identical. You can paste a UUID generated here directly into any GUID field in C#, .NET, SQL Server, or anywhere else GUIDs are accepted.
A UUID v4 has 122 random bits, giving roughly 5.3 × 10^36 possible values. The probability of generating a duplicate is so small that you would need to generate one billion UUIDs per second for about 85 years to have a 50% chance of a single collision. For practical purposes, treat them as unique.
Paste any UUID into the UUID Checker box and it instantly tells you if the format is valid, which version it is (v1, v3, v4, v5, v6, v7, v8 or Nil), which variant it belongs to, and — for v1 and v7 — the exact UTC timestamp encoded inside it. The checker also normalizes the formatting (lowercase, hyphenated) and works whether you paste it with braces, quotes, no hyphens, or in any case.
Yes. The UUID Checker on this page is a free online UUID validator — no installation, no signup, no API keys. Just paste the value and read the result. It runs entirely in your browser, so the UUIDs you check are never sent anywhere.
Yes — open Advanced settings, set the quantity field up to 1,000 and click Generate. All UUIDs are produced instantly in your browser. Use the "Copy All" button to put the entire list on your clipboard, or "Download .txt" to save them as a file. This is perfect for seeding databases, generating test data, or pre-allocating IDs.
Inside Advanced settings you can switch between lowercase (550e8400-e29b-41d4-a716-446655440000) and uppercase, toggle hyphens on/off (550e8400e29b41d4a716446655440000), and wrap each UUID in braces ({…}), quotes ("…"), or output them as a comma-separated list. These options make it easy to drop UUIDs straight into SQL, JSON, C#, JavaScript, or any other language.
It is 100% free with no signup, no ads in your output, and no tracking of the values you generate. All generation and validation happen client-side using your browser’s built-in cryptographic random number generator. We never see, log, or transmit any UUID you create or check — making it safe even for production credentials and database seeds.
A Nil UUID is the special value 00000000-0000-0000-0000-000000000000. It is used as a placeholder, sentinel value, or default when no real UUID is yet available. Many systems treat the Nil UUID as a "missing" or "not yet assigned" identifier — never use it as a real, unique key.