Free online UUID/GUID/ULID/NanoID generator supporting 5 unique ID formats, bulk generation up to 100, customizable formatting, and UUID validation. Ready to use instantly—perfect for database primary keys and test data creation.
UUID (Universally Unique Identifier) and GUID (Globally Unique Identifier) are essentially the same thing with different names: UUID is the formal IETF standard name (RFC 4122), while GUID is Microsoft's preferred term in the Windows ecosystem. Both share the identical 128-bit format like `550e8400-e29b-41d4-a716-446655440000`. Standard UUIDs generated by this tool work interchangeably in any scenario requiring GUIDs.
UUID v1 is based on timestamp and MAC address—time-ordered and traceable, but may leak MAC address information. UUID v4 is completely random, the most commonly used and secure choice, suitable for most primary key and identifier scenarios. UUID v5 is a SHA-1 hash-based namespaced version—same namespace + same name always produces the same UUID, ideal for deterministic output scenarios. For general development, UUID v4 is the default choice.
ULID (26 chars) is shorter than UUID (36 chars with hyphens) and lexicographically sortable by creation time, making it ideal for database indexes and log tracing. NanoID (21 chars default) is even shorter and faster, using URL-safe characters so no escaping is needed in URLs and cookies—it's about 30% smaller than UUID. All three have negligible collision probability, but ULID's sortability shines in distributed systems, while NanoID is friendlier for frontend/URL scenarios.
Yes. This tool supports bulk generation from 1 to 100 IDs. Set the count via quick buttons or the slider, then generate with one click—perfect for test data creation, bulk imports, and preparing unique IDs for scripts. After generation, you can copy all results at once or export as TXT or JSON files.
Bulk generation guideYes. Switch to the "Validate" tab and paste any string—the tool automatically identifies and validates: standard UUIDs (v1/v3/v4/v5) will report their specific version number, and it also recognizes ULID (26-char Crockford Base32) and NanoID (21-char URL-safe) formats, making it very convenient for quickly troubleshooting ID format issues during development and debugging.
Completely safe. All ID generation and validation runs locally in your browser via JavaScript, using crypto.getRandomValues() for cryptographically secure random numbers. No generated IDs are sent to any server, and no generation history is stored in the cloud. It works even when offline, making it suitable for enterprise intranets and sensitive projects.
Yes. For UUID v1/v4/v5, the tool provides two toggles: "Uppercase" switches the output case, and "Hyphens" lets you remove the dashes (useful for URLs, config files, or databases that require hyphen-free format). ULID and NanoID have no hyphens by default and also support case switching.
Command-line tools (like Linux's uuidgen, Python's uuid module) require a development environment. An online tool works instantly in your browser with no installation needed. Additionally, this tool integrates UUID version recognition, bulk export, and local history features—more convenient when working across devices (e.g., generating IDs for non-technical colleagues) or when you need IDs on the fly.
UUID (Universally Unique Identifier) is a 128-bit identifier standardized by the Open Software Foundation (OSF), defined in RFC 4122. Its purpose is to allow distributed systems to uniquely identify information without a central authority for ID assignment.
A standard UUID looks like `550e8400-e29b-41d4-a716-446655440000`, composed of 32 hexadecimal digits split into 5 groups (8-4-4-4-12) by hyphens. Theoretically, the collision probability of UUID v4 is about 1/10^36—if you generated 1 billion UUIDs per second for about 800 years, the probability of a single collision would be approximately 50%, which is negligible in practice.
UUIDs are widely used for database primary keys, distributed trace IDs, request IDs, log trace IDs, unique file naming, test data IDs, and session identifiers. Nearly all mainstream programming languages include built-in UUID generation libraries.
| Feature | UUID v4 | ULID | NanoID |
|---|---|---|---|
| Length | 36 chars (with hyphens) / 32 chars (no hyphens) | 26 chars | 21 chars (default) |
| Character Set | Hexadecimal (0-9a-f) | Crockford Base32 (32 chars) | URL-safe (64 chars) |
| Sortability | Unordered (random) | Time-ordered | Unordered (random) |
| URL-safe | Needs escaping (hyphens + alphanumeric) | Mostly safe (uppercase + digits) | Fully URL-safe |
| Generation Speed | Fast | Fast | ~60% faster than UUID |
| Collision Probability | 1/10^36 | 1/10^36 | 1/10^34 (at 21 chars) |
| Typical Use Cases | Database primary keys, general IDs | Distributed systems, log tracing | Short URLs, frontend IDs, cookies |
| Language | Code |
|---|---|
| JavaScript | crypto.randomUUID() // Modern browsers / Node.js 19+ |
| Python | import uuid; uuid.uuid4() |
| Java | UUID.randomUUID() |
| Go | github.com/google/uuid; uuid.New() |
| Bash/Linux | uuidgen or cat /proc/sys/kernel/random/uuid |
Modern browsers and Node.js 14.17+ have the Web Crypto API built in, allowing direct UUID v4 generation without third-party libraries.
// Modern browsers / Node.js 19+
const id = crypto.randomUUID();
console.log(id); // "550e8400-e29b-41d4-a716-446655440000"
// Node.js 14.17 - 18.x
const crypto = require('crypto');
const id = crypto.randomUUID();Use Python's standard library uuid module to bulk generate multiple UUID v4s, ideal for test data preparation.
import uuid
# Generate single UUID
uid = uuid.uuid4()
print(uid)
# Bulk generate 10 UUIDs
for _ in range(10):
print(uuid.uuid4())
# Generate uppercase UUID without hyphens
print(uuid.uuid4().hex.upper())Quickly generate UUIDs in Linux/macOS terminal, suitable for use in shell scripts.
# Linux uuidgen # macOS uuidgen | tr 'A-Z' 'a-z' # Direct read from system random file (most raw method) cat /proc/sys/kernel/random/uuid