# Presets

Presets cover env vars that a hosting platform sets on its own — deployment IDs, git metadata, region, and so on. Compose one into `createEnvironment` (or `generateEnvironmentExample`) via [`extends`](/env/extends) to type and validate a platform's vars alongside your app's own:

```ts
import { createEnvironment } from "@zap-studio/env";
import { vercel } from "@zap-studio/env/presets";
import { z } from "zod";

export const env = createEnvironment({
  extends: [vercel],
  server: { DATABASE_URL: z.string().url() },
  runtimeEnv: process.env,
});

env.VERCEL_GIT_COMMIT_SHA; // string | undefined
```

## Every Key Is Optional

Every preset key is typed `string | undefined`. These vars are only present when the app is actually running on that platform, and this package never reads or parses files, so it can't detect the platform itself — you decide which presets apply, usually by knowing where the app deploys.

## Available Presets

| Preset       | Platform         | Docs                                                                                                       |
| ------------ | ---------------- | ---------------------------------------------------------------------------------------------------------- |
| `vercel`     | Vercel           | [System environment variables](https://vercel.com/docs/environment-variables/system-environment-variables) |
| `netlify`    | Netlify          | [Read-only build variables](https://docs.netlify.com/build/configure-builds/environment-variables/)        |
| `render`     | Render           | [Environment variables](https://render.com/docs/environment-variables)                                     |
| `railway`    | Railway          | [Variables reference](https://docs.railway.com/variables/reference)                                        |
| `fly`        | Fly.io Machines  | [Runtime environment](https://fly.io/docs/machines/runtime-environment/)                                   |
| `coolify`    | Coolify          | [Predefined variables](https://coolify.io/docs/knowledge-base/environment-variables)                       |
| `cloudflare` | Cloudflare Pages | [Build configuration](https://developers.cloudflare.com/pages/configuration/build-configuration/)          |
| `denoDeploy` | Deno Deploy      | [Env vars and contexts](https://docs.deno.com/deploy/reference/env_vars_and_contexts/)                     |

All eight are available from `@zap-studio/env/presets` and can be imported individually — only the ones you import end up in your bundle.

```ts
import { cloudflare, denoDeploy, netlify, vercel } from "@zap-studio/env/presets";
```

## Composing Multiple Presets

Presets compose like any other `EnvironmentSchema` — pass more than one to `extends` if your app can run on more than one platform:

```ts
createEnvironment({
  extends: [vercel, cloudflare],
  runtimeEnv: process.env,
});
```

Presets never share keys with each other, so there's no conflict risk between them — see [`extends`](/env/extends) for how conflicts are detected in general.

## See Also

* [`extends`](/env/extends) — how schema composition and conflict detection work
* [Getting Started](/env/getting-started) — your first schema, without presets