How to Generate a UUID in JavaScript, Python, and SQL

JavaScript / Node.js

Modern browsers and Node.js (18+) support crypto.randomUUID() natively — no package install needed:

// Browser or Node.js 18+
const id = crypto.randomUUID();
console.log(id); // e.g. "3fa85f64-5717-4562-b3fc-2c963f66afa6"

For older Node.js versions, use the built-in crypto module or the popular uuid npm package:

// Node.js < 18, via built-in crypto module
const { randomUUID } = require('crypto');
const id = randomUUID();

// Or via the "uuid" npm package (npm install uuid)
import { v4 as uuidv4 } from 'uuid';
const id2 = uuidv4();

Python

Python's standard library has had UUID support built in since Python 2.5 — no pip install required:

import uuid

id = uuid.uuid4()
print(id)          # 3fa85f64-5717-4562-b3fc-2c963f66afa6
print(str(id))      # as a string
print(id.hex)        # without hyphens: 3fa85f6457174562b3fc2c963f66afa6

SQL

PostgreSQL

-- Postgres 13+: built-in, no extension needed
SELECT gen_random_uuid();

-- Older Postgres: enable the extension once
CREATE EXTENSION IF NOT EXISTS "pgcrypto";
SELECT gen_random_uuid();

-- As a table column default
CREATE TABLE users (
  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  name TEXT
);

MySQL

-- Built-in function, returns a UUID v1 (timestamp + MAC) by default
SELECT UUID();

-- MySQL stores it as a string (CHAR(36)) unless you convert it
INSERT INTO users (id, name) VALUES (UUID(), 'Alice');

SQL Server

-- Returns a GUID (Microsoft's UUID implementation)
SELECT NEWID();

-- As a table column default
CREATE TABLE users (
  id UNIQUEIDENTIFIER DEFAULT NEWID(),
  name NVARCHAR(100)
);

SQLite

-- No native UUID function — generate in application code
-- and store as TEXT, or use a random-blob expression:
SELECT lower(hex(randomblob(4)) || '-' || hex(randomblob(2)) || '-4' ||
  substr(hex(randomblob(2)),2) || '-' ||
  substr('89ab',abs(random()) % 4 + 1, 1) || substr(hex(randomblob(2)),2) || '-' ||
  hex(randomblob(6)));

Frequently Asked Questions