@neondatabase/serverless

@neondatabase/serverless is Neon's PostgreSQL driver for JavaScript and TypeScript. It's:

• Low-latency, thanks to message pipelining and other optimizations
• Ideal for serverless/edge deployment, using https and WebSockets in place of TCP
• A drop-in replacement for node-postgres, aka pg (on which it's based)

Get started

Install it

Install it with your preferred JavaScript package manager. It's named @neondatabase/serverless on npm and @neon/serverless on JSR. So, for example:

1npm install @neondatabase/serverless

or

1bunx jsr add @neon/serverless

Using TypeScript? No worries: types are included either way.

Configure it

Get your connection string from the Neon console and set it as an environment variable. Something like:

DATABASE_URL=postgres://username:password@host.neon.tech/neondb

Use it

For one-shot queries, use the neon function. For instance:

1import { neon } from '@neondatabase/serverless';
2const sql = neon(process.env.DATABASE_URL);
3
4const [post] = await sql`SELECT * FROM posts WHERE id = ${postId}`;
5// `post` is now { id: 12, title: 'My post', ... } (or undefined)

Note: interpolating ${postId} here is safe from SQL injection.

Deploy it

Turn this example into a complete API endpoint deployed on Vercel Edge Functions at https://myapp.vercel.dev/api/post?postId=123 by following two simple steps:

1. Create a new file api/post.ts:

1import { neon } from '@neondatabase/serverless';
2const sql = neon(process.env.DATABASE_URL);
3
4export default async (req: Request, ctx: any) => {
5  // get and validate the `postId` query parameter
6  const postId = parseInt(new URL(req.url).searchParams.get('postId'), 10);
7  if (isNaN(postId)) return new Response('Bad request', { status: 400 });
8
9  // query and validate the post
10  const [post] = await sql`SELECT * FROM posts WHERE id = ${postId}`;
11  if (!post) return new Response('Not found', { status: 404 });
12
13  // return the post as JSON
14  return new Response(JSON.stringify(post), {
15    headers: { 'content-type': 'application/json' }
16  });
17}
18
19export const config = {
20  runtime: 'edge',
21  regions: ['iad1'],  // specify the region nearest your Neon DB
22};

2. Test and deploy

1npm install -g vercel  # install vercel CLI
2npx vercel env add DATABASE_URL  # paste Neon connection string, select all environments
3npx vercel dev  # check working locally, then ...
4npx vercel deploy

The neon query function has a few additional options.

Sessions, transactions, and node-postgres compatibility

A query using the neon function, as shown above, is carried by an https fetch request.

This should work — and work fast — from any modern JavaScript environment. But you can only send one query at a time this way: sessions and transactions are not supported.

transaction()

Multiple queries can be issued via fetch request within a single, non-interactive transaction by using the transaction() function. This is exposed as a property on the query function.

For example:

1import { neon } from '@neondatabase/serverless';
2const sql = neon(process.env.DATABASE_URL);
3const showLatestN = 10;
4
5const [posts, tags] = await sql.transaction([
6  sql`SELECT * FROM posts ORDER BY posted_at DESC LIMIT ${showLatestN}`,
7  sql`SELECT * FROM tags`,
8]);

There are some additional options when using transaction().

Pool and Client

Use the Pool or Client constructors, instead of the functions described above, when you need:

• session or interactive transaction support, and/or

• compatibility with node-postgres, which supports query libraries like Kysely or Zapatos.

Queries using Pool and Client are carried by WebSockets. There are two key things to know about this:

1. In Node.js and some other environments, there's no built-in WebSocket support. In these cases, supply a WebSocket constructor function.

2. In serverless environments such as Vercel Edge Functions or Cloudflare Workers, WebSocket connections can't outlive a single request.

   That means Pool or Client objects must be connected, used and closed within a single request handler. Don't create them outside a request handler; don't create them in one handler and try to reuse them in another; and to avoid exhausting available connections, don't forget to close them.

These points are demonstrated in the examples below.

API

• The full API guide to Pool and Client can be found in the node-postgres docs.

• There are a few additional configuration options that apply to Pool and Client here.

Example: Node.js with Pool.connect()

In Node.js, it takes two lines to configure WebSocket support. For example:

1import { Pool, neonConfig } from '@neondatabase/serverless';
2
3import ws from 'ws';
4neonConfig.webSocketConstructor = ws; // <-- this is the key bit
5
6const pool = new Pool({ connectionString: process.env.DATABASE_URL });
7pool.on('error', (err) => console.error(err)); // deal with e.g. re-connect
8// ...
9
10const client = await pool.connect();
11
12try {
13  await client.query('BEGIN');
14  const {
15    rows: [{ id: postId }],
16  } = await client.query('INSERT INTO posts (title) VALUES ($1) RETURNING id', [
17    'Welcome',
18  ]);
19  await client.query('INSERT INTO photos (post_id, url) VALUES ($1, $2)', [
20    postId,
21    's3.bucket/photo/url',
22  ]);
23  await client.query('COMMIT');
24} catch (err) {
25  await client.query('ROLLBACK');
26  throw err;
27} finally {
28  client.release();
29}
30
31// ...
32await pool.end();

Other WebSocket libraries are available. For example, you could replace ws in the above example with undici:

1import { WebSocket } from 'undici';
2neonConfig.webSocketConstructor = WebSocket;

Example: Vercel Edge Function with Pool.query()

We can rewrite the Vercel Edge Function shown above (under the heading 'Deploy it') to use Pool, as follows:

1import { Pool } from '@neondatabase/serverless';
2
3// *don't* create a `Pool` or `Client` here, outside the request handler
4
5export default async (req: Request, ctx: any) => {
6  // create a `Pool` inside the request handler
7  const pool = new Pool({ connectionString: process.env.DATABASE_URL });
8
9  // get and validate the `postId` query parameter
10  const postId = parseInt(new URL(req.url).searchParams.get('postId'), 10);
11  if (isNaN(postId)) return new Response('Bad request', { status: 400 });
12
13  // query and validate the post
14  const [post] = await pool.query('SELECT * FROM posts WHERE id = $1', [postId]);
15  if (!post) return new Response('Not found', { status: 404 });
16
17  // end the `Pool` inside the same request handler
18  // (unlike `await`, `ctx.waitUntil` won't hold up the response)
19  ctx.waitUntil(pool.end());
20
21  // return the post as JSON
22  return new Response(JSON.stringify(post), {
23    headers: { 'content-type': 'application/json' }
24  });
25}
26
27export const config = {
28  runtime: 'edge',
29  regions: ['iad1'],  // specify the region nearest your Neon DB
30};

Note: we don't actually use the pooling capabilities of Pool in this example. But it's slightly briefer than using Client and, because Pool.query is designed for one-shot queries, we may in future automatically route these queries over https for lower latency.

Example: Vercel Edge Function with Client

Using Client instead, the example looks like this:

1import { Client } from '@neondatabase/serverless';
2
3// don't create a `Pool` or `Client` here, outside the request handler
4
5export default async (req: Request, ctx: any) => {
6  // create a `Client` inside the request handler
7  const client = new Client(process.env.DATABASE_URL);
8  await client.connect();
9
10  // get and validate the `postId` query parameter
11  const postId = parseInt(new URL(req.url).searchParams.get('postId'), 10);
12  if (isNaN(postId)) return new Response('Bad request', { status: 400 });
13
14  // query and validate the post
15  const [post] = await client.query('SELECT * FROM posts WHERE id = $1', [postId]);
16  if (!post) return new Response('Not found', { status: 404 });
17
18  // end the `Client` inside the same request handler
19  // (unlike `await`, `ctx.waitUntil` won't hold up the response)
20  ctx.waitUntil(client.end());
21
22  // return the post as JSON
23  return new Response(JSON.stringify(post), {
24    headers: { 'content-type': 'application/json' }
25  });
26}
27
28export const config = {
29  runtime: 'edge',
30  regions: ['iad1'],  // specify the region nearest your Neon DB
31};

More examples

These repos show how to use @neondatabase/serverless with a variety of environments and tools:

• Raw SQL + Vercel Edge Functions
• Raw SQL via https + Vercel Edge Functions
• Raw SQL + Cloudflare Workers
• Kysely + Vercel Edge Functions
• Zapatos + Vercel Edge Functions

Bring your own Postgres database

This package comes configured to connect to a Neon database. But you can also use it to connect to your own Postgres instances if you run your own WebSocket proxy.

Open-source

This code is released under the MIT license.

Feedback and support

Please visit Neon Community or Support.