🚀 Introduction

When building backend systems with Node.js, TypeScript, and Prisma ORM, you’ll often instantiate a PrismaClient to communicate with your database.

However, one of the most common mistakes developers make — even experienced ones — is creating multiple Prisma clients unintentionally.

This may not break your app immediately, but over time (especially in development or under load), it leads to:

• Database connection leaks
• “Too many connections” errors
• Slow queries and degraded performance
• Memory bloat from redundant connection pools

Let’s understand why this happens, and how to solve it cleanly and permanently using the Prisma Singleton Pattern.

The Problem: Multiple PrismaClient Instances

The Prisma client maintains a connection pool to your database.

When you do this:

import { PrismaClient } from '@prisma/client';
const prisma = new PrismaClient();

You create a new pool of connections.

In production, your code executes once — no problem.

But in development, tools like:

• Nodemon
• ts-node-dev
• Next.js