> ## Documentation Index
> Fetch the complete documentation index at: https://docs.jolter.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Configuration

> Reference for `jolter.json` schema v2, runtimes, tools, plugins, and legacy compatibility.

Jolter projects use `jolter.json`. Schema version 2 supports one runtime, multiple tools, and optional plugin requirements.

## Complete schema example

```json jolter.json theme={null}
{
  "$schema": "https://schemas.jolter.dev/project/v2/schema.json",
  "schemaVersion": 2,
  "runtime": {
    "node": "24.x"
  },
  "tools": {
    "npm": "11.x",
    "pnpm": "10.x",
    "yarn": "4.x",
    "eslint": "8.x"
  },
  "plugins": {
    "@eslint/eslint": "1.x"
  }
}
```

All fields are optional, but `sync`, `repair`, and `setup-ci` require a resolvable runtime from `jolter.json`, `.node-version`, or `.nvmrc`.

## Top-level fields

| Field           | Type    | Meaning                                  |
| --------------- | ------- | ---------------------------------------- |
| `$schema`       | string  | Optional JSON Schema URL                 |
| `schemaVersion` | integer | Current schema version, `2`              |
| `runtime`       | object  | Zero or one of `node`, `bun`, or `deno`  |
| `tools`         | object  | Built-in tools and plugin-provided tools |
| `plugins`       | object  | Plugin provider requirements             |

Unknown fields fail validation. Unknown schema versions fail closed.

## Runtime rules

Valid:

```json theme={null}
{
  "runtime": {
    "bun": "1.x"
  }
}
```

Invalid:

```json theme={null}
{
  "runtime": {
    "node": "24",
    "deno": "2"
  }
}
```

A project can configure only one runtime.

## Tool rules

Built-in tools:

```json theme={null}
{
  "runtime": {
    "node": "24"
  },
  "tools": {
    "pnpm": "10",
    "yarn": "4"
  }
}
```

Plugin tools:

```json theme={null}
{
  "runtime": {
    "node": "24"
  },
  "tools": {
    "eslint": "8"
  },
  "plugins": {
    "@eslint/eslint": "1"
  }
}
```

Plugin versions and tool versions are separate.

## Legacy input compatibility

Schema version 1 and the earlier map-valued `packageManager` key remain accepted as input compatibility. When Jolter rewrites configuration, it emits the canonical `tools` key.

This is different from the standard string-valued `package.json#packageManager` field:

```json package.json theme={null}
{
  "packageManager": "pnpm@10.12.1"
}
```

## Creating and updating config

Use `pin`:

```bash theme={null}
jolter pin node@24
jolter pin pnpm@10
jolter pin eslint@8
```

Then validate:

```bash theme={null}
jolter sync
jolter doctor
```

Commit `jolter.json`. Do not commit `JOLTER_HOME` or installed runtime directories.


## Related topics

- [Compatibility](/reference/compatibility.md)
- [Plugins overview](/plugins/overview.md)
- [Networking and offline mode](/operations/networking-and-offline.md)
- [Team onboarding](/guides/team-onboarding.md)