# On Express

{% hint style="success" %}
This is the official documentation of the `@forestadmin/agent` Node.js agent.
{% endhint %}

If you already have an application running using [Express](https://expressjs.com/), the easiest way to attach the Forest Admin agent would use the `mountOnExpress` function, just like in the following example:

```javascript
require('dotenv').config();

const { createAgent } = require('@forestadmin/agent');
const { createSqlDataSource } = require('@forestadmin/datasource-sql');
const express = require('express');

const agent = createAgent({
  authSecret: process.env.FOREST_AUTH_SECRET,
  envSecret: process.env.FOREST_ENV_SECRET,
  isProduction: process.env.NODE_ENV === 'production',
});

const app = express();

// This function must be called before other middlewares.
await agent.mountOnExpress(app).start();

app.listen(3000);
```