# Next.js, adding features just to development mode

> Learn how to enable features only in development mode in Next.js by checking process.env.NODE_ENV, so API routes, pages, or JSX stay hidden in production.

Author: [Flavio Copes](https://flaviocopes.com/about/) | Published: 2021-06-25 | Topics: [Next.js](https://flaviocopes.com/tags/next/) | Canonical: https://flaviocopes.com/nextjs-development-only/

Some sites/apps I work on have 2 modes. One is the development mode, the other is production, the live version.

With [Next.js](https://flaviocopes.com/nextjs/) I find this very easy to do so by checking the value of `process.env.NODE_ENV`, which is set to `'development'` when running it with `npm run dev`.

So I might have an API route that should not be public, and at the top of it, I add

```js
if (process.env.NODE_ENV != 'development') return null
```

so it does not work in production.

The same applies to a page component, which will render a blank page if accessed in production.

I use the same technique to add JSX to a component only in development mode:

```jsx
{
  process.env.NODE_ENV == 'development' && <div>hi</div>
}
```