# Bun (/docs/guides/runtimes/bun)

Scaffold a Prisma ORM app with Bun, run your first typed query, serve users over HTTP, and deploy to Prisma Compute.

Location: Guides > Runtimes > Bun

## Introduction

In this guide, you scaffold a Prisma ORM project with Bun, initialize a PostgreSQL database from your schema, run your first typed query, serve query results over HTTP with `Bun.serve`, and deploy the server to [Prisma Compute](/guides/deploy-compute). Bun runs TypeScript directly, so nothing has to be compiled to work locally; the deploy bundles the server with `tsdown`.

Every command and code sample below was run end to end against a live Prisma Postgres database.

## Prerequisites

- [Bun](https://bun.sh/) 1.1 or later (`bun --version`)
- A PostgreSQL connection string, or nothing at all: `bunx create-db` can create a [Prisma Postgres](/guides/introduction-2-postgres) database for you

## Use with your agent

To delegate this guide to your coding agent, copy the prompt below and hand it over:

```text
Create a new Bun app with Prisma ORM, run a first typed query, and deploy it to Prisma Compute.

1. Scaffold: `bun create prisma@latest my-bun-app --template minimal --provider postgres --package-manager bun --yes`. Then run `bunx prisma@latest init` in `my-bun-app` so the Prisma agent skills are installed and stay current, and use them. Get a database connection string: use the one I give you, or create a Prisma Postgres database with `bunx create-db` and show me the claim URL it prints. Export it as `DATABASE_URL` in the shell; the generated scripts read the environment variable, not `.env`.
2. In `my-bun-app`, run `bun run contract:emit`, then `bun run db:init`, with `DATABASE_URL` exported.
3. Replace `src/index.ts` with a script that creates a user and reads all users back via `db.orm.public.User`, following https://www.prisma.io/docs/guides/runtimes/bun.md, and verify `bun src/index.ts` prints the created user (`bun run dev` is `tsx watch`, which does not exit).
4. Add `src/server.ts` with a `Bun.serve` server exposing GET /users, and verify `curl http://localhost:3000/users` returns the users.
5. Deploy: check `bunx prisma@latest auth whoami`; if I am not signed in, stop and ask me to run `bunx prisma@latest auth login`. Then point the build at the server by setting `entry` in `tsdown.config.ts` to `{ server: "src/server.ts" }`, run `bun run build`, then `bunx prisma@latest deploy module.ts`, and verify the live URL's /users endpoint returns `[]`. The deployed app provisions its own fresh Prisma Postgres database, so the local users are not there; do not pass the local DATABASE_URL. If the deploy fails with `HostedStateBootstrapError`, a project with the module's name exists in my workspace but its hosted state cannot be verified; re-run the deploy with `--name <a unique name>`.

Use the installed Prisma ORM skills.
```

## 1. Scaffold the project

Create the project with `create-prisma`. Pick Bun as the package manager when prompted, or pass everything up front:

```bash
bun create prisma@latest my-bun-app --template minimal --provider postgres --package-manager bun --no-deploy
```

Answer the prompts for contract authoring style and agent skills. The scaffold sets up `src/prisma/` with a starter schema and installs dependencies with Bun.

```bash
cd my-bun-app
```

Next, set the database connection for the local steps. Use your own PostgreSQL connection string, or create a Prisma Postgres database with `bunx create-db`; it prints a connection string and a claim URL you can open to keep the database. Export the variable in the shell you work in; the generated scripts read the environment variable, not `.env`:

```bash
export DATABASE_URL="<your connection string>"
```

## 2. Emit the contract and initialize the database

Prisma ORM compiles your schema (`src/prisma/contract.prisma`) into a contract that your queries are type-checked against. If you chose TypeScript authoring (`--authoring typescript`), the source is `src/prisma/contract.ts` and the emitted files land in `src/prisma/generated/` instead. Emit it, then apply the schema to the database:

```bash
bun run contract:emit
bun run db:init
```

`db:init` creates the tables and signs the database:

```text no-copy
"summary": "Applied 5 operation(s) across 1 space(s), database signed"
```

If `db:init` stops with `Connection terminated unexpectedly`, a database you just created is still starting; wait a few seconds and run it again. The command is safe to repeat and reports `Applied 0 operation(s)` when there is nothing left to do.

If `db:init` reports that the contract file is missing, run `bun run contract:emit` first; the emit step generates `src/prisma/contract.json`.

## 3. Write your first query

Replace `src/index.ts` with a script that creates a user and reads every user back. Model access is namespace-qualified on PostgreSQL: `db.orm.public.User`, where `public` is the default schema.

```ts title="src/index.ts"
import { db } from "./prisma/db";

// Create a user, then read every user back
const user = await db.orm.public.User.create({
  email: `ada+${Date.now()}@prisma.io`,
  name: "Ada Lovelace",
});
console.log(`created user ${user.email}`);

const users = await db.orm.public.User.select("id", "email", "name").all();
console.log(`there are now ${users.length} users`);

await db.close();
```

`await db.close()` at the end lets the script exit cleanly; without it, the connection pool keeps the process alive.

## 4. Run it

The generated `dev` script is `tsx watch src/index.ts`, which re-runs the file on every save. For a single run, call Bun directly:

```bash
bun src/index.ts
```

```text no-copy
created user ada+1784893846026@prisma.io
there are now 1 users
```

The `pg` driver may print an SSL mode deprecation warning above the output; it comes from the `sslmode=require` setting in the generated connection string and does not affect the query.

That is the whole loop: schema to contract, contract to database, typed queries against both.

## 5. Serve it over HTTP

The script pattern works for one-off jobs. To keep the app running and serve query results, add a small HTTP server with `Bun.serve`. Create `src/server.ts`:

```ts title="src/server.ts"
import { db } from "./prisma/db";

const server = Bun.serve({
  port: Number(process.env.PORT ?? 3000),
  async fetch(req) {
    const { pathname } = new URL(req.url);
    if (pathname === "/users") {
      const users = await db.orm.public.User.select("id", "email", "name").all();
      return Response.json(users);
    }
    return new Response("Not found", { status: 404 });
  },
});

console.log(`Listening on http://localhost:${server.port}`);
```

Start it and check the endpoint:

```bash
bun src/server.ts
```

```bash
curl http://localhost:3000/users
```

```json no-copy
[{ "id": 1, "email": "ada+1784893846026@prisma.io", "name": "Ada Lovelace" }]
```

The server listens on port 3000; set `PORT` to change it. Unlike the script, the server never calls `db.close()`: the connection pool is shared across requests and closes when the process exits.

## 6. Deploy to Prisma Compute

Plain Bun servers are supported on [Prisma Compute](/guides/deploy-compute). The scaffold declares the app for [Prisma Composer](/guides/build-composer) in `module.ts` and `service.ts`, which deploy whatever the `build` script bundles into `dist/server.mjs`. That script runs `tsdown`, and the generated `tsdown.config.ts` sets its entry to `src/index.ts`, so point the entry at your server instead:

```ts title="tsdown.config.ts"
export default defineConfig({
  entry: { server: "src/server.ts" },
  // the rest of the generated config is unchanged
});
```

Sign in once (it opens a browser):

```bash
bunx prisma@latest auth login
```

Then build and deploy from the project directory:

```bash
bun run build
bunx prisma@latest deploy module.ts
```

```text no-copy
my-bun-app
├─ database   postgres-database db_abc123
└─ app        compute-service cps_abc123
              https://xyz.ewr.prisma.build
```

The deploy creates a project named after your module in your workspace, and re-running the deploy reuses it: the CLI finds the hosted state it stored on the first run and converges the project to your module. If a project with that name exists but the CLI cannot identify or verify its stored state (one left behind by a different checkout, for example), the deploy stops with `HostedStateBootstrapError`; deploy under another name with `--name <unique-name>`, or rename the module in `module.ts`. The deploy also provisions its own Prisma Postgres database on the platform, declared in `module.ts`; the users you created locally are not in it. Verify the live endpoint responds with an empty list from the fresh database:

```bash
curl https://xyz.ewr.prisma.build/users
```

```json no-copy
[]
```

For previews per Git branch and deploy on push, see [Deploy on push](/guides/integrations-deploy-on-push).

## Prompt your coding agent

Run [`bunx prisma@latest init`](/guides/platform-init) once to install the [Prisma ORM skills](/guides/tools-skills#available-skills-for-prisma-orm-8) for your coding agent and keep them matching your installed packages. Prompts that map to this guide:

- "Using the prisma-8 skill, add a script that lists the 10 newest users."
- "Add a published flag to the Post model in the starter contract, emit the contract, and update the database."

## Next steps

- [Learn the fundamentals](/guides/fundamentals-reading-data): filtering, sorting, pagination, and writes.
- [Read the Prisma ORM overview](/guides/introduction-2-orm) for the concepts behind contracts and typed queries.

## Related pages

- [`Deno`](/guides/guides-3-runtimes-deno): Run a minimal Prisma ORM and PostgreSQL app on Deno.

## Related pages

- [Authentication & Tools](./authentication-tools-index.md)
- [Build](./build-index.md)
- [Changelog](../changelog.md)
- [Concepts](./concepts-index.md)
- [Console commands](./console-commands-index.md)
- [Contract Authoring](./contract-authoring-index.md)
- [Core Concepts](./core-concepts-index.md)
- [Data Modeling](./data-modeling-index.md)
- [Database](./database-index.md)
- [DB commands](./db-commands-index.md)

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