¿Qué UUID debo usar como clave primaria en PostgreSQL?

UUID v7 o ULID son los más recomendados hoy: incluyen timestamp en los primeros bits, por lo que los índices B-Tree insertan en orden y evitan fragmentación. UUID v4 es aleatorio y puede degradar el rendimiento de índices en tablas grandes.

¿Se envían mis identificadores a algún servidor?

No. Toda la generación e inspección ocurre en tu navegador con JavaScript y la Web Crypto API. Puedes desconectar internet después de cargar la página y seguir usándola.

¿Puedo extraer la fecha de creación de un UUID?

Sí, para UUID v1, v7 y ULID. La pestaña Inspector decodifica el timestamp embebido y muestra hora local, UTC y tiempo transcurrido desde la creación.

DEVELOPMENT & DATABASES

Generator & Inspector of UUID (v4, v7) & ULID

Create globally unique identifiers, decode embedded timestamps, and export batches for databases — nothing ever leaves your browser.

100% local generation with crypto.getRandomValues() — no ID is sent to any server.

Version

Count: 500

Type the exact amount of IDs to generate (e.g. 500, 10,000, 100,000). Up to 500 IDs are rendered onscreen for performance, while file export includes all records.

Format

Code snippets (Dev Mode)

Native examples to generate the selected type in your stack.

import { uuidv7 } from "uuidv7";

const id = uuidv7();
console.log(id);

Unique Identifier Architecture (RFC 9562 & ULID)

Technical benchmark comparing random UUID v4, time-ordered UUID v7, and ULID specs.

UUID v7 (RFC 9562): The New Database Standard

Standardized in RFC 9562, UUID v7 pairs a 48-bit UNIX epoch timestamp with 74 bits of entropy, yielding time-ordered primary keys with zero B-Tree index fragmentation.

UUID v4: 122 Bits of Pure Randomness

UUID v4 offers 122 bits of pseudo-random entropy. Ideal for session tokens and secrets where concealing issuance timing is required.

B-Tree Fragmentation & Page Splits

Random UUID v4 inserts scatter randomly across leaf nodes, forcing expensive page splits. Sequential UUID v7 appends directly to the rightmost leaf.

ULID: 26 Crockford Base32 Characters

ULID compresses 128 bits into 26 sortable characters using Crockford Base32, eliminating ambiguous glyphs (I, L, O, U) for safe URL embedding.

UUID, Database Indexing & Scale Troubleshooting

Step-by-step fixes for slow INSERT throughput, collision myths, and binary storage types.

Issue 1

Database `INSERT` Latency Spikes on Tables Over 1M Rows

⚡ Quick Fix:Switch your primary key generator from UUID v4 to UUID v7 to restore append-only sequential writes.

🔧 Technical Fix:Store keys as native `UUID` in PostgreSQL or `BINARY(16)` in MySQL to prevent Buffer Pool cache trashing.

Issue 2

Wasted Storage & Cache Loss from Storing UUIDs as `VARCHAR(36)`

⚡ Quick Fix:Use native `UUID` (16 bytes) or `BINARY(16)` instead of 36-byte strings to cut index size in half.

🔧 Technical Fix:Leverage MySQL's `UUID_TO_BIN(val, 1)` to swap timestamp bits into optimized index locations.

Issue 3

Security & Privacy Leak: MAC Address Exposure in Legacy UUID v1

⚡ Quick Fix:Deprecate UUID v1 in user-facing applications and adopt UUID v7 or v4.

🔧 Technical Fix:UUID v1 embeds physical hardware MAC addresses in the node field, exposing topology to attackers.

Issue 4

UI Freeze when Generating Massive Batches (50,000+ IDs)

⚡ Quick Fix:This tool limits DOM nodes to 500 while streaming all IDs directly to an in-memory Blob export.

🔧 Technical Fix:Use writable streaming pipelines (`fs.createWriteStream`) in backends to generate millions of IDs without memory leaks.

Did You Know? UUID & ULID Trivia

Astronomical probabilities, the 2024 RFC 9562 milestone, and human-friendly Base32 alphabets.

🌌

More UUID v4 Combinations Than Observable Stars

122 bits offer 5.3 × 10^36 unique combinations. Generating 1 billion UUIDs every second for 85 years yields just a 50% chance of a single collision.

📅

RFC 9562 Took Nearly 20 Years to Succeed RFC 4122

Published in May 2024, RFC 9562 officially updated the 2005 RFC 4122 specification to standardize time-ordered UUID v6, v7, and v8.

0️⃣

The Nil and Max UUID Boundary Constants

RFC standards define Nil (`0000...0000`) and Max (`ffff...ffff`) as mathematical boundary markers for queries.

🔤

Why ULID Excludes Letters I, L, O, and U

Crockford Base32 drops 'I' and 'L' (confusion with 1), 'O' (confusion with 0), and 'U' to eliminate unintended profanities in generated IDs.

Cryptographic Identifiers (UUID / ULID) Glossary

Learn the fundamental concepts, protocols, and technical terminology of this tool.

UUID v4Criptografía

What is a UUID version 4?

A 128-bit Universally Unique Identifier generated entirely from cryptographic pseudo-random entropy, rendering collision chances virtually zero.

UUID v7 (Time-Ordered)Bases de Datos

Why is UUID v7 better for databases than v4?

Combines a 48-bit Unix timestamp prefix with random entropy, facilitating natural chronological ordering that avoids B-Tree database page fragmentation.

ULID (Universally Unique Lexicographically Sortable Identifier)APIs

What is a ULID?

A 26-character Base32 identifier that is lexicographically sortable, URL-safe, hyphens-free, and optimized for distributed systems.

Espacio de Entropía & ColisionesMatemáticas

Can two identical UUIDs ever be generated?

With 122 bits of true random entropy, one would need to generate 1 billion UUIDs every second for a century to hit a 50% duplicate probability.