# How do I build my first app?

> Open a sheet, describe the tool in plain words, check the sandbox preview, click Deploy. The app lands in your Drive as an Apps Script web app with a URL.

Source: https://docs.applane.dev/builders/first-app/

**Who:** Builder  
**Time:** 10 minutes

An app in Applane is a Google Apps Script web app. You describe it, the agent writes it inside a fixed template, you see it run in a preview, and you deploy it. It lands in your Drive with a URL on `script.google.com`.

## 1. Start from data

Open the sheet, doc or folder you want the tool to work on, then open the side panel. The agent can read what you point it at; a sheet with clear column headers is the best first input.

Click **New app**. Pick the audience: **Internal** for a tool your colleagues open with their work account. That is the right choice for a first app; the other two are explained in [Sharing an app](https://docs.applane.dev/builders/sharing/).

## 2. Describe it

Write what the tool should do in plain words, as you would to a colleague. Say which sheet or table it reads, what a person does with it, and what it should write back, if anything. For example:

> A form to log a customer visit. Read the customer list from the "Accounts" tab, let me pick one, add a date, a contact and notes, and append the visit to the "Visits" tab.

The agent reads the sheet's headers, writes the app, and shows it in the preview.

## 3. Look at the preview

The preview runs the app in a sandbox inside the panel, against your real data, with your own account. Click through it. If something is wrong, say so in the next message: "the date should default to today", "sort accounts by name". Each turn goes through the same validator, so the app never leaves the template.

## 4. Deploy

Click **Deploy**. Applane creates an Apps Script project in your Drive (or updates it), pushes the files and creates a web-app deployment. You get a URL.

An internal app runs as whoever opens it, and Google only lets in accounts at your domain. Nobody can see data through it that they could not already see themselves.

## 5. Come back later

Your apps are listed on the panel's home screen, along with the apps shared with you. Open one to keep building; the source is pulled from the Apps Script project, so it works from any machine. The project is also visible at [script.google.com](https://script.google.com) like any other.

## What the agent can and cannot do

It reads sheets, docs and the BigQuery tables your company allows, and writes app code. It cannot change the app's permissions, share it, publish it to partners or the public, or run a BigQuery query above the cost limit without asking you. Those are yours: [Sharing an app](https://docs.applane.dev/builders/sharing/).

Chat history and drafts stay in your browser. Nothing you type reaches Applane; the model runs in your company's own GCP project.