# prettyJSON

**Kind:** Function

**Source:** [`src/middleware/pretty-json/index.ts`](https://github.com/honojs/hono/blob/main/src/middleware/pretty-json/index.ts#L46)

**Part of:** [Middleware](subsystem-src-middleware)

Pretty JSON Middleware for Hono.

`prettyJSON` creates Hono middleware that formats JSON response bodies with indentation when the request asks for pretty output. Register it before route handlers so it can inspect downstream JSON responses and replace them with formatted JSON when appropriate.

## Signature

```ts
function prettyJSON(options: PrettyOptions): MiddlewareHandler
```

## Parameters

| Name | Type |
|---|---|
| `options` | `PrettyOptions` |

**Returns:** `MiddlewareHandler`

## Diagram

```mermaid
graph LR
  Request[Incoming request] --> Middleware[prettyJSON middleware]
  Middleware --> Route[Route handler]
  Route --> Response[JSON response]
  Response --> Middleware
  Middleware --> Formatted[Formatted JSON response]
```

## Usage

```ts
import { Hono } from 'hono'
import { prettyJSON } from 'hono/pretty-json'

const app = new Hono()

app.use('*', prettyJSON())

app.get('/users', (c) => {
  return c.json({
    users: [{ id: 'user-a', name: 'Ada' }],
  })
})

export default app
```

Request the route with `?pretty` to receive formatted JSON.

## AI Coding Instructions

- Register `prettyJSON()` before routes whose JSON responses should support formatted output.
- Return JSON through Hono response helpers such as `c.json()` so the response has a JSON content type.
- Preserve the middleware order: `prettyJSON` must wrap downstream route handling to format the completed response.
- Avoid applying assumptions about non-JSON response bodies; the middleware should only reformat valid JSON responses.