# Generate UUID v4 identifiers

> Generate one or up to 1000 UUID v4 IDs at a time, in lowercase, uppercase, no-hyphens, or {braces} format.

Open the tool: https://yourbrowsercandoit.com/uuid-generator

Generate UUID v4 identifiers locally. Free, no signup. Runs entirely in your browser; files are never uploaded.

## How it works

Built on crypto.randomUUID, the browser's standard cryptographically-secure UUID v4 generator. Set the quantity (1 to 1000) and pick a format: default (lowercase with hyphens, e.g. 550e8400-e29b-41d4-a716-446655440000), uppercase, no hyphens (550e8400e29b41d4a716446655440000, for compact storage), or {braces} (Windows GUID style, {550e8400-e29b-41d4-a716-446655440000}). The output is one UUID per line, ready to copy. UUID v4 uses 122 bits of randomness, giving a collision probability so vanishingly small (1 in 2^61 for a billion IDs generated by the same source) that it's safe to use as a primary key across distributed systems without coordination.

## How to use it

1. **Set the quantity.** Generate 1 to 1000 UUIDs at once.
2. **Pick a format.** Lowercase with hyphens, UPPERCASE, no hyphens, or {braces} Windows GUID style.
3. **Generate and copy.** One UUID per line, produced by the browser's CSPRNG — safe for keys and tokens.

## Frequently asked questions

### What's UUID v4?

A 128-bit identifier with 122 bits of pure randomness. Version 4 means it's random (not derived from time or namespace). The collision probability is negligible at any practical scale.

### Are they cryptographically secure?

Yes. crypto.randomUUID uses the browser's CSPRNG. Safe for use as opaque identifiers, session tokens, and primary keys.

### Can I generate UUID v1, v5, or v7?

Not in this tool. Only v4. v1 (time-based) and v5 (namespace-based) are less commonly used; v7 (time-sortable) isn't widely supported in browsers yet.

### Are the UUIDs uploaded?

No. Generated locally via the browser's Web Crypto API.

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