UUID / ID Generator

How to Use the UUID Generator

This free online UUID generator creates unique identifiers in multiple formats including UUID v4, NanoID, ULID, and CUID. Whether you're assigning primary keys in a database, generating session tokens, or creating unique filenames, this tool lets you batch-generate up to 50 IDs at once with a single click — all entirely in your browser.

Step-by-Step

Choose your format — Select from UUID v4, NanoID, ULID, or CUID depending on your use case.

Set the batch size — Generate 1 to 50 IDs at once using the quantity control.

Click Generate — Your unique identifiers appear instantly.

Copy to clipboard — Copy a single ID or the entire batch with one click.

ID Formats Explained

UUID v4 — The standard 128-bit RFC 4122 identifier (550e8400-e29b-41d4-a716-446655440000). Universally supported across databases, APIs, and programming languages.

NanoID — A compact 21-character URL-safe ID (V1StGXR8_Z5jdHi6B-myT). Smaller than UUID with the same collision resistance. Perfect for URLs and client-side IDs.

ULID — Lexicographically sortable unique ID using Crockford's Base32 encoding. Includes a timestamp component so IDs sort chronologically — ideal for time-series data.

CUID — Collision-resistant ID designed for distributed systems. Safe for horizontal scaling across multiple servers without coordination.

Common Use Cases

Database Primary Keys — Generate UUID v4 or ULID values for primary keys in PostgreSQL, MongoDB, or DynamoDB without relying on auto-increment sequences.

API Idempotency Keys — Create unique request IDs to prevent duplicate processing in payment APIs (Stripe, PayPal) and order systems.

Session and Token Generation — Generate NanoIDs for session identifiers, invitation codes, or short-lived tokens that need to be URL-safe.

File and Resource Naming — Create unique filenames for S3 uploads, cache keys, or temporary files to avoid collisions.

Distributed System IDs — Use CUIDs when generating IDs across multiple microservices or edge functions that can't coordinate through a central authority.

Tips for Power Users

- **UUID v4** is the safest default choice — it's supported everywhere and has effectively zero collision probability (122 random bits).

- **ULID** is ideal when you need IDs that sort by creation time without a separate timestamp column. Great for event logs and time-series databases.

- **NanoID** produces shorter IDs than UUID (21 chars vs. 36 chars), making it more efficient for URLs. Use a URL shortener pattern like /invite/V1StGXR8_Z5jdHi6B-myT.

- Batch generation is perfect for seeding databases, creating test fixtures, or preparing bulk import files.

- All IDs are generated using the browser's crypto.getRandomValues() API, which provides cryptographically secure random numbers.

Why Use This Tool?

This UUID generator runs entirely in your browser using the Web Crypto API for cryptographically secure random number generation. No server is involved — your generated IDs are never transmitted or logged. It's the fastest, most private way to generate unique identifiers for development, testing, and production use.