# Introduction (/docs)



`@vlandoss/env` lets you describe every variable your app expects in a single [Standard Schema](https://github.com/standard-schema/standard-schema) contract (Zod, Valibot, ArkType…), then resolves it against per-environment config files and your environment variables at boot. Missing or malformed values fail the process before user code ever reads them.

The core is **runtime-agnostic** — Node, Bun, Deno, browsers, Workers, Edge. File-based config loading lives in a separate, opt-in entrypoint so the core stays portable, and client-side adapters (Vite plugin, React `<EnvScript />`) ship as their own optional entrypoints too.

## The shape of a typical setup [#the-shape-of-a-typical-setup]

The contract — every variable your app expects, grouped into branches.

```ts title="src/env/schema.ts"
import { schema, type Config } from "@vlandoss/env";
import * as z from "zod";

export const Env = schema({
  server: {
    HOST: z.string(),
    PORT: z.coerce.number().int().positive()
  },
  db: {
    URL: z.string()
  },
});

export type EnvConfig = Config<typeof Env>;
```

The wiring — combine the schema with per-environment config and surface a single typed `env` object.

```ts title="src/env/index.ts"
import { defineEnv } from "@vlandoss/env";
import { loadConfig } from "@vlandoss/env/fs";
import { Env } from "./schema.ts";

export const env = defineEnv({
  schema: Env,
  config: loadConfig(Env)
});
```

`env.server.PORT` is `number`. Reading anything not in the schema is a compile error.

## Entrypoints [#entrypoints]

| Entrypoint                                         | Runtime           | Description                                                                       |
| -------------------------------------------------- | ----------------- | --------------------------------------------------------------------------------- |
| [`@vlandoss/env`](/docs/api-reference/core)        | Any               | The core — declare schemas and resolve a typed env at boot.                       |
| [`@vlandoss/env/fs`](/docs/api-reference/fs)       | Node / Bun / Deno | Discover and load per-environment config files from disk.                         |
| [`@vlandoss/env/vite`](/docs/api-reference/vite)   | Build time        | Vite plugin that wires config and the current env name into your bundle.          |
| [`@vlandoss/env/react`](/docs/api-reference/react) | SSR / SSG         | React component that ships the server-resolved env to the browser.                |
| [`@vlandoss/env/zod`](/docs/api-reference/zod)     | Any               | Opinionated Zod primitives for common env-var shapes (`port`, `host`, `bool`, …). |

## Where to go next [#where-to-go-next]

* **[Getting started](/docs/getting-started/installation)** — install and wire up a minimal Node app.
* **[Concepts](/docs/concepts/overview)** — the mental model: resolution order, env-var naming, `envName()` precedence.
* **[Guides](/docs/guides)** — recipes per runtime (Node, SPA, SSR) and per task (composition, custom modes).
* **[API reference](/docs/api-reference)** — every export, organized by entrypoint.
* **[Community](/docs/community)** — contribute, file issues, and follow Variable Land.