UUID Generator

Related

What is a UUID?

Use Cases

• Generate UUID v4 as table record primary keys during database design to avoid data volume leakage from auto-increment IDs
• Use ULID as sortable global request/trace IDs in distributed systems or microservice architectures
• Bulk generate UUIDs as test data and mock order/user IDs during API development and integration testing
• Use NanoID instead of UUID in frontend short links or share URLs—shorter, cleaner, no URL encoding needed
• Use UUID v5 to generate deterministic IDs from fixed namespaces, ensuring same input always produces same output
• Use the validation feature to identify ID type and version when encountering unknown-format IDs in debug logs or third-party documentation

How to Use

1. Select the desired ID type from the cards above: UUID v4 (recommended), v1, v5, ULID, or NanoID
2. If choosing UUID v5, enter a namespace string; other IDs can directly set format options
3. Toggle uppercase and hyphen options as needed, set bulk generation count (1-100) via quick buttons or slider
4. Click the generate button to view results—copy individually, copy all at once, or export as TXT/JSON
5. To validate an existing ID, switch to the "Validate" tab and paste the ID string to get type and version info

Features

• Five ID types in one tool: UUID v1 (timestamp), v4 (random), v5 (namespace), ULID (sortable), and NanoID (URL-safe)—one tool covers all tech stack needs
• UUID validation & recognition: Switch to the Validate tab, paste any ID to identify its UUID version or detect ULID/NanoID format—fast troubleshooting during debugging
• Bulk generate up to 100: Generate any quantity from 1 to 100 IDs at once—no more manually copying one by one for test data
• Flexible formatting: Toggle uppercase and hyphens for UUIDs to match database, URL, and config file format requirements
• Export & local history: One-click copy all, export TXT/JSON files, generation history saved locally for instant recovery—bulk operations more efficient
• Client-side secure random: Uses browser crypto API for cryptographically secure random numbers, IDs never leave your device, works offline

Code Examples

// 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();

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())

# Linux
uuidgen

# macOS
uuidgen | tr 'A-Z' 'a-z'

# Direct read from system random file (most raw method)
cat /proc/sys/kernel/random/uuid

Which Unique ID Scheme Should You Choose?

UUID isn't the only option—database auto-increment IDs and Snowflake are also mainstream primary key schemes. Decide first based on 'data scale, need for global uniqueness, and need for time-based sorting' to avoid many detours.

Best Practices

FAQ

Glossary

UUID

Universally Unique Identifier, 128-bit length, RFC 4122 standard, common versions include v1 (timestamp+MAC), v4 (random), v5 (SHA-1 hash).

GUID

Globally Unique Identifier, Microsoft's term for UUID—the two are identical in format and purpose.

ULID

Universally Unique Lexicographically Sortable Identifier, 26 characters using Crockford Base32 encoding, first 48 bits are timestamp—sortable by creation time.

NanoID

A lightweight unique ID generator, 21 URL-safe characters by default (A-Za-z0-9_-), shorter and faster than UUID, ideal for frontend and URL scenarios.

UUID v1

Timestamp and MAC address-based UUID version, time-sortable but may leak MAC address and generation time—less secure than v4.

UUID v4

Completely random number-based UUID version, most widely used, negligible collision probability, the default choice in development.

UUID v5

SHA-1 hash-based namespaced UUID version—same namespace + same name input produces identical UUID output, suitable for deterministic scenarios.

Collision Probability

The probability that two randomly generated IDs are identical. UUID v4's collision probability is about 1 in 17 billion trillion, negligible in practical engineering.

Crockford Base32

A Base32 encoding designed by Douglas Crockford that uses uppercase letters and digits excluding I/L/O/U to avoid ambiguous characters—used by ULID.

UUID / ULID / NanoID Comparison

UUID Generation Methods by Language

Authoritative References

• IETFRFC 4122 - UUID Specification
• GitHubULID Specification (GitHub)
• OfficialNanoID Official Site