What is the difference between a UUID and a GUID?

UUID (Universally Unique Identifier) is a 128-bit identifier standardized by RFC 4122 and RFC 9562. GUID (Globally Unique Identifier) is Microsoft's implementation of the UUID specification. In modern computing, UUID and GUID are effectively synonymous.

When should I use UUID v4 vs UUID v7?

Use UUID v4 for cryptographically random, unpredictable identifiers (such as session tokens or security IDs). Use UUID v7 for database primary keys where time-ordered (lexicographically sortable) IDs prevent B-Tree index fragmentation while retaining global uniqueness.

Is UUID v7 universally better than UUID v4?

No. UUID v7 provides time-ordered properties useful for database indexing and sorting scenarios. However, because v7 embeds a timestamp in the first 48 bits, it reveals the creation time of the ID. Use v4 if creation timestamps must remain private.

What does the UUID Inspector / Parser do?

Paste any UUID string (hyphenated, unhyphenated, braced, or URN) to inspect its RFC version (v1, v3, v4, v5, v7), variant, embedded timestamp & creation date (for v1 and v7), clock sequence, and node ID.

Which UUID versions are supported for generation?

Our tool supports Version 1 (MAC + timestamp), Version 4 (cryptographically random), Version 5 (SHA-1 namespace + name hash), and Version 7 (Unix Epoch millisecond time-ordered).

Can I generate bulk UUIDs and export them?

Yes. You can generate up to 10,000 UUIDs per batch and export the list in TXT, CSV, or JSON format with custom casing and hyphen formatting.

What input formats does the validator support?

The validator supports standard hyphenated UUIDs, unhyphenated 32-hex strings, braced GUIDs ({...}), uppercase/lowercase, and URN format (urn:uuid:...).

Is my generated or parsed UUID stored on any server?

No. All generation, parsing, formatting, and validation logic runs 100% locally inside your web browser. No data is stored in localStorage or transmitted over the network.

How does UUID v5 namespace hashing work?

UUID v5 uses SHA-1 hashing to combine a namespace UUID (such as DNS or URL) with a specific name string. The same namespace and name will always generate the exact same deterministic UUID.

What is the difference between UUID and ULID?

Both UUID v7 and ULID are 128-bit time-ordered identifiers. ULID uses Base32 encoding for a 26-character string, while standard UUID v7 uses 36-character hyphenated hexadecimal format.

UUID & GUID Generator, Parser & Validator

Structure Breakdown

UUID Version

Version 4 (Cryptographically Random)

Variant

RFC 4122 / DCE 1.1

Braced GUID Format

{550e8400-e29b-41d4-a716-446655440000}

No-Hyphens Format

550e8400e29b41d4a716446655440000

UUID Version Standard Comparative Guide

Version	Generation Basis	Sortability	Recommended Use Cases
UUID v1	Gregorian Timestamp + Node MAC Address	Partial	Legacy distributed systems requiring host identification.
UUID v3 / v5	MD5 (v3) / SHA-1 (v5) Namespace + Name Hash	Non-sortable	Deterministic IDs created from URLs, domain names, or OIDs.
UUID v4	Cryptographically Random Number (PRNG)	Non-sortable	General application IDs, session tokens, API keys, privacy-sensitive IDs.
UUID v7	Unix Epoch Millisecond Timestamp + PRNG	Lexicographically Sortable	Database primary keys (SQL/NoSQL) to prevent B-Tree index fragmentation.

When to choose UUID v4 vs UUID v7

Choose UUID v4 when:

Creation timestamp MUST remain secret or obscured.
Generating API tokens, session cookies, or security nonces.
IDs are not used as clustered database primary keys.

Choose UUID v7 when:

IDs serve as primary keys in B-Tree indexed databases (PostgreSQL, MySQL).
Time-ordered sorting is required without adding a separate `created_at` index column.
High write-throughput distributed event logging.

What is a UUID / GUID?

A Universally Unique Identifier (UUID) or Globally Unique Identifier (GUID) is a 128-bit identifier formatted as 32 hexadecimal digits separated by hyphens (8-4-4-4-12). It provides a globally unique key without requiring a central registration authority.

UUID v4 (Cryptographically Random)

UUID v4 uses cryptographically secure pseudo-random numbers (CSPRNG via Web Crypto API) to generate unique IDs. With 122 bits of entropy, the odds of a duplicate collision are virtually zero (1 in 5.3x10^36).

UUID v7 (Time-Ordered & Database Index Optimized)

UUID v7 encodes a 48-bit Unix timestamp at the beginning of the identifier followed by random bits. This ensures sequential sorting in database B-Tree indexes (MySQL, PostgreSQL, MongoDB), drastically reducing page splits compared to random UUID v4.

UUID v1 (Timestamp & MAC) vs UUID v5 (SHA-1 Namespace)

UUID v1 combines a 60-bit timestamp with node hardware info. UUID v5 generates deterministic IDs by hashing a namespace UUID and a string name using SHA-1, making it repeatable for given inputs.

100% Cryptographic In-Browser Security

All single and bulk UUID generation calls leverage `crypto.getRandomValues()` directly inside your browser. Generated IDs are never transmitted or saved to external databases.

Explore Related Developer Utilities

Convert timestamps with our <a href="/unix-timestamp-converter" class="text-cyan-400 hover:underline font-semibold">Unix Timestamp Converter</a>, hash data using <a href="/hash-generator" class="text-cyan-400 hover:underline font-semibold">Hash Generator</a>, decode tokens via <a href="/jwt-decoder" class="text-cyan-400 hover:underline font-semibold">JWT Decoder</a>, and format payloads with <a href="/json-formatter" class="text-cyan-400 hover:underline font-semibold">JSON Formatter</a>.

UUID & GUID Generator, Parser & Validator

UUID & GUID Generator, Parser & Validator

UUID Generation Parameters

Generated Output

UUID / GUID Inspector Input

Structure Breakdown