UUID Generator Suite | v1, v4, v6, v7 & ULID Tools (2026) 2026 — Free Online Tool

UUID stands for Universally Unique Identifier. It is a 128-bit number standardized by RFC 4122 (and updated by RFC 9562) used to uniquely identify information in computer systems without requiring a central coordinator. UUIDs are formatted as 32 hexadecimal characters in 8-4-4-4-12 grouping, e.g., 'e464800e-d6f4-4eb3-8aef-a6ddfe9badbe'.

UUID v1 uses the host's MAC address and timestamp (not privacy-friendly). UUID v4 uses 122 bits of cryptographically secure random data (most common, privacy-friendly). UUID v7 (RFC 9562) combines a 48-bit Unix timestamp with random bits, making it both time-sortable and random — ideal for database primary keys with sequential B-tree index insertion.

There are 2^122 (approximately 5.3 × 10^36) possible UUID v4 values. To put this in perspective, you would need to generate 1 billion UUIDs per second for approximately 85 years to have a 50% chance of a single collision (birthday paradox). UUIDs are designed so that collisions in practice are virtually impossible.

UUID v4 is cryptographically secure when generated using a secure random number generator (CSPRNG) like the Web Cryptography API's crypto.getRandomValues(). UUID v1 is NOT cryptographically secure because it embeds the host's MAC address and timestamp, making it predictable. UUID v7 is secure because it uses CSPRNG for the random portion.

UUID (Universally Unique Identifier) and GUID (Globally Unique Identifier) are essentially the same thing. UUID is the standard term from RFC 4122 / RFC 9562, while GUID is Microsoft's terminology (used in Windows COM, .NET). Microsoft GUIDs are binary-compatible with UUIDs.

In modern JavaScript, use the Web Crypto API: crypto.randomUUID() returns a v4 UUID like 'e464800e-d6f4-4eb3-8aef-a6ddfe9badbe'. For Node.js (version 14.17+), the same API works. For older browsers, use the npm package 'uuid' or implement v4 generation using crypto.getRandomValues().

Use UUID v7 for database primary keys because: 1) It embeds a timestamp, so records are naturally sorted by creation time, 2) It improves B-tree index performance by reducing page fragmentation, 3) It still maintains 74 bits of randomness, making collisions practically impossible. Use UUID v4 only when you need truly opaque, unguessable identifiers (e.g., public-facing tokens).

ULID (Universally Unique Lexicographically Sortable Identifier) is a 128-bit identifier like UUID, but uses Crockford Base32 encoding (26 characters instead of 36) and is time-ordered. ULIDs are case-insensitive, URL-safe, and monotonically increasing. Example: '01ARZ3NDEKTSV4RRFFQ69G5FAV'. They are popular alternatives to UUID v7.

Nano ID is a tiny, secure, URL-friendly unique string ID generator for JavaScript. It uses a larger alphabet (64 characters: A-Za-z0-9_-) than UUID, allowing you to use shorter IDs (21 chars by default) with the same or better collision resistance. Use Nano ID for short URLs, user-facing references, or when storage size matters.

Yes, but only from v1, v6, and v7 UUIDs. For v1 and v6, decode the first 48 bits of the time field (with the Gregorian epoch offset 122192928000000000). For v7, simply parse the first 48 bits as a Unix millisecond timestamp. Our online tool has a built-in UUID timestamp extractor that automatically detects and displays the creation time.

In Python, use the built-in `uuid` standard module: `import uuid; print(uuid.uuid4())`. This generates a cryptographically random UUID v4 string (e.g., '123e4567-e89b-12d3-a456-426614174000'). For hex format without dashes, use `uuid.uuid4().hex`.

In Java, use the `java.util.UUID` class: `UUID uuid = UUID.randomUUID(); System.out.println(uuid.toString());`. Java uses SecureRandom under the hood to generate a 128-bit random UUID v4 string.

A Minecraft UUID generator converts a player's username or offline account name into a valid 128-bit UUID format. Offline Minecraft UUIDs use v3 MD5 hashing (`UUID.nameUUIDFromBytes(("OfflinePlayer:" + username).getBytes())`), while online player UUIDs are assigned directly by Mojang auth servers.

Snowflake ID is a 64-bit time-sortable ID format developed by Twitter (now X). It uses a 41-bit timestamp, 10-bit machine ID, and 12-bit sequence number. It is smaller than a 128-bit UUID, making it popular for high-throughput messaging systems and databases where 64-bit integers are preferred.

Yes, the NIL UUID ('00000000-0000-0000-0000-000000000000') is a special reserved UUID defined in RFC 4122. It represents the 'absence of a UUID' and is used in some protocols as a null value. The Max UUID ('ffffffff-ffff-ffff-ffff-ffffffffffff') is also reserved. Both are valid UUIDs but should not be generated randomly.

UUID version 8 is reserved in RFC 9562 for custom or experimental UUIDs. It allows organizations to define their own meaning for the bits. The format is: 48-bit custom timestamp | 4-bit version (8) | 12-bit custom | 2-bit variant (10) | 62-bit custom. Some implementations use v8 for company-specific identifiers or blockchain hashes.

To validate a UUID: 1) Check length (36 characters including hyphens, 32 without), 2) Verify hex characters (0-9, a-f, A-F), 3) Confirm version digit (1-7 in the 13th position), 4) Verify variant bits (8, 9, a, or b in the 17th position). Our free online tool validates UUIDs and shows the version, variant, and creation timestamp (for v1/v7).

Technically, UUIDs are case-insensitive (RFC 4122 specifies lowercase canonical form). The string 'E464800E-D6F4-4EB3-8AEF-A6DDFE9BADBE' and 'e464800e-d6f4-4eb3-8aef-a6ddfe9badbe' represent the same UUID. However, some systems normalize to lowercase. ULIDs and Nano IDs are case-sensitive.