[Kysely](https://kysely.dev) is a type-safe TypeScript SQL query builder that provides TypeScript support and a fluent API for building SQL queries. In this guide, you'll learn how to connect Kysely to [Prisma Postgres](/postgres) and start querying your database with full type safety.

## Prerequisites

- Node.js version 14 or higher
- TypeScript version 4.6 or higher (5.4+ recommended for improved type inference, 5.9+ for better compilation performance)
- Strict mode enabled in your `tsconfig.json` for Kysely's type safety

## 1. Create a new project

Create a new directory for your project and initialize it with npm:

```terminal
mkdir kysely-quickstart
cd kysely-quickstart
npm init -y
```

Install TypeScript and initialize it:

```terminal
npm install --save-dev typescript
npx tsc --init
```

## 2. Configure TypeScript

Kysely requires TypeScript's strict mode for proper type safety. Update your `tsconfig.json` file:

```json file=tsconfig.json
{
  // ...
  "compilerOptions": {
    // ...
    // add-start
    "strict": true,
    "allowImportingTsExtensions": true,
    "noEmit": true
    // add-end
    // ...
  }
  // ...
}
```

:::note

The `strict: true` setting is **required** for Kysely's type safety to work correctly.

:::

In your `package.json`, set the `type` to `module`:

```json
{
// ...
// add-start
"type": "module"
// add-end
// ...
}
```

## 3. Create a Prisma Postgres database

You can create a Prisma Postgres database using the `create-db` CLI tool. Follow these steps to create your Prisma Postgres database:

```terminal
npx create-db
```

Then the CLI tool should output:

```terminal
┌  🚀 Creating a Prisma Postgres database
│
│  Provisioning a temporary database in us-east-1...
│
│  It will be automatically deleted in 24 hours, but you can claim it.
│
◇  Database created successfully!
│
│
●  Database Connection
│
│
│    Connection String:
│
│    postgresql://hostname:password@db.prisma.io:5432/postgres?sslmode=require
│
│
◆  Claim Your Database
│
│    Keep your database for free:
│
│    https://create-db.prisma.io/claim?CLAIM_CODE
│
│    Database will be deleted on 11/18/2025, 1:55:39 AM if not claimed.
│
└  
```

Create a `.env` file and add the connection string from the output:

```env file=.env
DATABASE_URL="postgresql://hostname:password@db.prisma.io:5432/postgres?sslmode=require"
```

:::warning

**Never commit `.env` files to version control.** Add `.env` to your `.gitignore` file to keep credentials secure.

:::

The database created is temporary and will be deleted in 24 hours unless claimed. Claiming moves the database into your [Prisma Data Platform](https://console.prisma.io) account. Visit the claim URL from the output to keep your database.

:::note

To learn more about the `create-db` CLI tool, see the [create-db documentation](/postgres/introduction/npx-create-db).

:::

## 4. Install dependencies

Install Kysely and the PostgreSQL driver:

```terminal
npm install kysely pg dotenv
npm install --save-dev @types/pg tsx
```

**Package breakdown:**
- `kysely`: The type-safe SQL query builder
- `pg`: PostgreSQL driver for Node.js (required by Kysely's PostgresDialect)
- `dotenv`: Loads environment variables from `.env` file
- `@types/pg`: TypeScript type definitions for the pg driver
- `tsx`: TypeScript execution engine for running `.ts` files directly

## 5. Define database types

Create a `src/types.ts` file to define your database schema types:

```typescript file=src/types.ts
import type { Generated } from "kysely";

export interface Database {
  users: UsersTable;
}

export interface UsersTable {
  id: Generated<number>;
  email: string;
  name: string | null;
}
```

## 6. Configure database connection

Create a `src/database.ts` file to instantiate Kysely with your Prisma Postgres connection:

```typescript file=src/database.ts
import 'dotenv/config'
import type { Database } from './types.ts'
import { Pool } from 'pg'
import { Kysely, PostgresDialect } from 'kysely'

// Parse DATABASE_URL into connection parameters
function parseConnectionString(url: string) {
  const parsed = new URL(url)
  return {
    host: parsed.hostname,
    port: parseInt(parsed.port),
    user: parsed.username,
    password: parsed.password,
    database: parsed.pathname.slice(1), // Remove leading '/'
  }
}

const connectionParams = parseConnectionString(process.env.DATABASE_URL!)

const dialect = new PostgresDialect({
  pool: new Pool({
    ...connectionParams,
    ssl: true,
    max: 10,
  })
})

// Database interface is passed to Kysely's constructor, and from now on, Kysely 
// knows your database structure.
// Dialect is passed to Kysely's constructor, and from now on, Kysely knows how 
// to communicate with your database.
export const db = new Kysely<Database>({
  dialect,
})
```

## 7. Run queries

Create a `src/script.ts` file:

```typescript file=src/script.ts
import { db } from './database.ts'

async function main() {
  // Create the users table
  await db.schema
    .createTable('users')
    .ifNotExists()
    .addColumn('id', 'serial', (col) => col.primaryKey())
    .addColumn('email', 'varchar(255)', (col) => col.notNull().unique())
    .addColumn('name', 'varchar(255)')
    .execute()

  // Insert a user
  const user = await db
    .insertInto('users')
    .values({
      email: 'alice@prisma.io',
      name: 'Alice',
    })
    .returningAll()
    .executeTakeFirstOrThrow()

  console.log('Created user:', user)

  // Query all users
  const users = await db
    .selectFrom('users')
    .selectAll()
    .execute()

  console.log('All users:', users)
}

main()
  .then(async () => {
    await db.destroy()
  })
  .catch(async (error) => {
    console.error('Error:', error)
    await db.destroy()
    process.exit(1)
  })
```

Run the script:

```terminal
npx tsx src/script.ts
```

You should receive the following output:

```terminal
Created user: { id: 1, email: 'alice@prisma.io', name: 'Alice' }
All users: [ { id: 1, email: 'alice@prisma.io', name: 'Alice' } ]
```

## Next steps

You've successfully connected Kysely to Prisma Postgres! For more advanced features like schemas, migrations, and complex queries, see the [Kysely documentation](https://kysely.dev/docs/intro).

---

# Use Prisma Postgres with Drizzle ORM