A Practical Guide: Building a Simple Invoicing App with AppSheet and Google
A Practical Guide: Building a Simple Invoicing App with AppSheet and Google
By: The One Click Enterprise Team | April 21, 2025
Chasing down invoice details, manually calculating totals, and trying to keep track of what's paid and what's overdue... For many small business owners in South Africa, invoicing is a time-consuming but necessary chore that steals focus from more important work.
What if you could generate and send a professional PDF invoice directly from your phone in seconds? What if your app automatically tracked the status of every invoice you send?
This isn't a feature of expensive, complex accounting software. It's something you can build yourself, right now, with two tools you probably already use: Google Sheets and Google AppSheet. This guide will walk you through the basic steps to show you just how accessible this powerful technology is.
Step 1: Set Up Your "Database" in Google Sheets
Every app needs a 'brain' to store its data. For our invoicing app, a simple Google Sheet is the perfect database. The key is to structure your data logically across different tabs (sheets).
Create a new Google Sheet and set up three tabs with these columns:
Customers Tab:
CustomerID, Customer Name, Email Address, Phone Number, Physical Address
Invoices Tab:
InvoiceID, CustomerID (to link to the customer), Invoice Date, Due Date, Status (e.g., Draft, Sent, Paid), Total Amount
Invoice Items Tab:
ItemID, InvoiceID (to link to the invoice), Item Description, Quantity, Unit Price, Line Total
This structure is the foundation of your entire application.
Step 2: Connect Your Google Sheet to AppSheet
Now, let's bring your data to life. We need to tell AppSheet where to find your spreadsheet so it can turn it into an app.
Go to AppSheet.com and sign in with your Google account.
Click "Start with existing data".
Give your app a name, like "My Invoicing App".
Choose a category, like "Sales & CRM".
Select your new Google Sheet from your Google Drive.
In just a few moments, AppSheet will analyze your spreadsheet tabs and—like magic—generate a basic but functional app with views for your Customers, Invoices, and Invoice Items.
Step 3: Customize Your App's Views and Forms
The basic app works, but now we can make it more intuitive and professional using AppSheet's visual editor.
Improve Forms: When you add a new invoice, you can set the Invoice Date column to automatically default to today's date. For the Status column, you can create a simple dropdown menu with options like "Draft," "Sent," and "Paid."
Create Relationships: You can tell AppSheet that the CustomerID column in your Invoices table is related to your Customers table. Now, when you create a new invoice, you can select an existing customer from a dropdown list instead of re-typing their details!
Step 4: Add "Actions" to Automate Tasks
This is where the real power comes in. Actions are buttons in your app that perform tasks for you, turning a multi-step manual process into a single tap.
Let's create a "Send Invoice" button. We can configure this button in AppSheet to automatically perform a sequence of tasks:
Generate a professional PDF invoice based on a template you design.
Change the invoice Status in your data from "Draft" to "Sent."
Save the PDF to a specific folder in your Google Drive.
Create a pre-written email, attach the new PDF invoice to it, and send it directly to the correct customer's email address.
With this one Action, a five-minute manual process is now done flawlessly in five seconds.
In just these four steps, you've conceptually gone from a static spreadsheet to a powerful, custom business application that can save you hours every single month. This is just the beginning. You could add features to track payments against invoices, send automated reminders for overdue accounts, or create a dashboard to view your monthly sales totals.
Building your first app is an empowering experience. But if you want to unlock the full potential of AppSheet or need a more complex, polished solution without the learning curve, that's where an expert partner comes in.
At One Click Enterprise, we are certified AppSheet developers. We specialize in building the exact tools that South African businesses need to thrive.
Contact us for a free automation consultation to discuss your specific business processes.