> This page location: Backend > Neon Functions > Overview
> Full Neon documentation index: https://neon.com/docs/llms.txt

> Summary: Neon Functions are serverless compute you deploy onto a Neon branch. Host an API, AI agent, real-time server, or webhook handler that runs next to your Postgres data, with DATABASE_URL injected automatically.

# Neon Functions

Deploy a backend onto your Neon branch, next to your data.

Neon Functions are serverless compute you deploy onto a Neon branch, so your backend code runs right next to your database. Use them to host an API, an AI agent, a real-time server, or a webhook handler without standing up separate infrastructure.

What makes Neon Functions different from lambda-style serverless?

- **Next to your data.** Same region as the branch, with `DATABASE_URL` (plus [AI Gateway](https://neon.com/docs/ai-gateway/overview) and [Object Storage](https://neon.com/docs/storage/overview) credentials) injected automatically. No cross-region hops, and no credentials to wire up.
- **Long-running.** Start responding within 15 minutes, then keep streaming while data flows, so agents and WebSocket/SSE servers aren't cut off by a short execution limit. They're still serverless: idle functions can be evicted (see [Runtime limits](https://neon.com/docs/compute/functions/reference/runtime-limits)).
- **Branches with your data.** Each branch runs its own function at its own URL against its own database state.

Functions run on Neon's own compute platform, the same infrastructure that runs your Postgres, so they sit in the same region as your data.

> During the private preview, Functions are available for **new projects** in the **AWS us-east-2** region only, created on or after June 15, 2026. See [Preview access](https://neon.com/docs/compute/functions/preview-access) for what's included.

## Request/response, not background jobs

A function is always requested (by a `fetch`, a browser, an agent) and always returns a web response: JSON, an HTTP stream, an SSE feed, or a WebSocket upgrade.

That makes functions a fit for request/response work, and not for background jobs. Background jobs and workflows are the other kind of compute: queued, retryable, cancellable work with its own lifecycle, like sending a welcome email after signup. Those need a job queue or workflow engine to own that lifecycle. Today you can pair a function with a third-party queue or scheduler like [Upstash QStash](https://upstash.com/docs/qstash) or [Inngest](https://www.inngest.com): the service owns the queue, retries, and scheduling, and invokes your function over HTTP to run each job. A native Neon job queue and workflow engine is a separate, upcoming offering.

Any module whose default export provides a `fetch(request)` method that returns a `Response` is a function. It embraces the web platform standards: the Fetch API's `Request` and `Response` interface, the same handler shape used by other serverless runtimes and standardized by [WinterTC](https://wintertc.org/). That can be an object with a `fetch` method:

```ts
export default {
  fetch: (request: Request) => new Response('Hello world'),
};
```

Or a bare async function:

```ts
export default async function handler(request: Request) {
  return new Response('Hello world');
}
```

A [Hono](https://hono.dev) app exports the object shape, so `export default app` works directly. Hono is the recommended framework.

## When to use Neon Functions

- **REST APIs and CRUD backends**: request in, JSON out, queries running next to Postgres. See [Get started](https://neon.com/docs/compute/functions/get-started).
- **AI agents**: stream tokens back across multiple model calls and tool invocations without a short execution limit cutting the run off. See [AI agents](https://neon.com/docs/compute/functions/agents).
- **Real-time apps**: WebSocket servers for chat and presence, or SSE for live updates. See [WebSockets and SSE](https://neon.com/docs/compute/functions/websockets).
- **MCP servers**: expose database-backed tools to AI clients over a single `fetch` endpoint. See the [with-mcp example](https://github.com/neondatabase/examples/tree/main/with-mcp).
- **File upload APIs**: receive a file, write it to [Object Storage](https://neon.com/docs/storage/overview), return a result.
- **Webhook handlers and bots**: receive events and query Postgres in the same region.

## How Functions fit with your app

Functions are backend primitives, not full-stack app hosting. Host your app on Vercel, Netlify, or another frontend host; reach for a function for the long-running, stateful slice of your backend that belongs next to your data. Two common shapes:

- **Add a function to a full-stack app.** Your Next.js or TanStack Start app owns the UI, auth, and most routes. When one workload outgrows the host's short serverless limit (a WebSocket or SSE server, or a long-running agent), move only that piece onto a function and call it directly from the client. See [Authentication](https://neon.com/docs/compute/functions/authentication) for the direct-call pattern.
- **Run the backend on functions.** When the frontend is client-only (a React or TanStack SPA), the client calls functions directly: REST APIs, request/response agents, MCP servers, and anything stateful that belongs close to Postgres and Object Storage.

## Get started

- [Preview access](https://neon.com/docs/compute/functions/preview-access): Request access and learn what's included in the private preview.
- [Get started](https://neon.com/docs/compute/functions/get-started): Deploy your first function and call it over HTTP in under 5 minutes.
- [AI agents](https://neon.com/docs/compute/functions/agents): Run streaming, tool-calling AI agents next to your data.
- [WebSockets and SSE](https://neon.com/docs/compute/functions/websockets): Hold long-lived connections open with WebSockets or SSE.
- [Authentication](https://neon.com/docs/compute/functions/authentication): Verify callers before a function does any work.
- [Environment variables](https://neon.com/docs/compute/functions/environment-variables): Neon-injected variables and how to add your own secrets.
- [Deploy and manage](https://neon.com/docs/compute/functions/deploy): CLI and API reference for deploying and managing functions.
- [Runtime limits](https://neon.com/docs/compute/functions/reference/runtime-limits): Timeouts, slug constraints, memory, and other hard limits.

## Examples and templates

Each example is a complete, runnable build. Read the source on GitHub, or scaffold one with `neon bootstrap --template <id>` (it copies the files, links a Neon project, and pulls env vars). You can also browse them at [build-on-neon.vercel.app](https://build-on-neon.vercel.app/).

| Example                  | `--template`    | Source                                                                                      | Neon services                                   | Stack                 |
| ------------------------ | --------------- | ------------------------------------------------------------------------------------------- | ----------------------------------------------- | --------------------- |
| REST API                 | `hono`          | [with-hono](https://github.com/neondatabase/examples/tree/main/with-hono)                   | Functions, Postgres                             | Hono, Drizzle         |
| Image-generation agent   | `ai-sdk`        | [with-ai-sdk](https://github.com/neondatabase/examples/tree/main/with-ai-sdk)               | Functions, Postgres, AI Gateway, Object Storage | AI SDK, Drizzle       |
| Personal-assistant agent | `mastra`        | [with-mastra](https://github.com/neondatabase/examples/tree/main/with-mastra)               | Functions, Postgres, AI Gateway                 | Mastra                |
| MCP server               | `mcp`           | [with-mcp](https://github.com/neondatabase/examples/tree/main/with-mcp)                     | Functions, Postgres                             | Hono, Drizzle         |
| Realtime chat            | `realtime-chat` | [with-realtime-chat](https://github.com/neondatabase/examples/tree/main/with-realtime-chat) | Functions, Postgres, Neon Auth                  | Next.js, Hono         |
| Realtime counter         | `realtime-sse`  | [with-realtime-sse](https://github.com/neondatabase/examples/tree/main/with-realtime-sse)   | Functions, Postgres                             | TanStack Router, Hono |

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## Related docs (Neon Functions)

- [Preview access](https://neon.com/docs/compute/functions/preview-access)
- [Get started](https://neon.com/docs/compute/functions/get-started)
- [Deploy and manage](https://neon.com/docs/compute/functions/deploy)
- [Environment variables](https://neon.com/docs/compute/functions/environment-variables)
- [Authentication](https://neon.com/docs/compute/functions/authentication)
- [AI agents](https://neon.com/docs/compute/functions/agents)
- [WebSockets and SSE](https://neon.com/docs/compute/functions/websockets)

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