Google Sheets SaaS: Enterprise-Grade Financial Automation Sidebar App

A Google Sheets sidebar app with a custom SPA and REST API workflow that turns spreadsheet-based financial data entry into a controlled, high-integrity operational system.

Overview

This project shows how a familiar spreadsheet workflow can be upgraded into a more reliable operational system without forcing a team to abandon Google Sheets.

By embedding a Vue.js SPA directly inside the Google Sheets sidebar, I created a controlled interface for financial data entry that validates data in real time , communicates with a backend REST API, and reduces the kinds of errors that happen when users type directly into cells.

For small finance, bookkeeping, or operations teams, this is the kind of approach that preserves the convenience of spreadsheets while adding the structure, validation, and workflow control of a more serious internal tool.

Demo (Video)

Business value

1. Safer data entry

Standard spreadsheets let people type almost anything anywhere. This sidebar app replaces that with a more guided, validated workflow, helping teams reduce manual mistakes before bad data spreads through the system.

2. API-connected operations

Instead of keeping the sheet isolated, the interface connects to a backend API for template loading, controlled inputs, and structured workflow steps. That turns the spreadsheet into part of a broader operational system .

3. Better fit for real teams

Many small businesses are not ready to move fully into a custom SaaS product. This kind of build gives them a practical middle ground: keep the spreadsheet environment they know, but add stronger controls and automation where they matter most.

4. Strong foundation for future internal tools

Once a team is using a sidebar app like this, it becomes easier to expand into approval flows, multi-user workflows, reporting, and deeper internal tooling later.

Tech Stack

• Frontend: Vue.js and TypeScript
• Backend Integration: REST API via Fetch/Axios
• Runtime: Google Apps Script (GAS)
• Security: Script Properties Service for secrets/license keys
• Deployment path: Google Workspace Marketplace

What this project demonstrates

• building custom interfaces inside spreadsheet environments
• using APIs to make Sheets part of a larger business workflow
• improving data integrity without forcing a full rebuild
• combining frontend UX with operational automation

This is the kind of project I can adapt for teams that rely on Google Sheets but need more reliable workflows, cleaner data entry, or tighter integration with their backend systems.