# Excel Management Web Application

A lightweight, high-performance web application to upload, view, and download Excel spreadsheets (`.xlsx` and `.xls`) with a Google Sheets-like table interface.

## Features

- **Dashboard**:
  - Clean view of available Excel files with filenames, sizes, upload timestamps, and sheet counts.
  - Drag-and-drop or click-to-browse Excel file uploader supporting `.xlsx` and `.xls`.
  - Click any file card to open its complete spreadsheet view.

- **Spreadsheet Viewer (Google Sheets style)**:
  - Column letters (`A`, `B`, `C`...) pinned above headers with sticky scrolling.
  - Row numbers (`1`, `2`, `3`...) pinned on the left with sticky scrolling.
  - Cell borders, alignment, and readable fonts.
  - Multi-worksheet switching via bottom/top worksheet tabs.
  - Progressive rendering chunking for high performance on large datasets.

- **Download**:
  - Prominent **Download Original Excel** button to download the authentic file with full fidelity.

- **Navigation**:
  - One-click **Back to Dashboard** navigation.
  - Currently active filename badge.

## How to Run

1. Open your terminal in this directory:
   ```bash
   npm start
   ```
2. Open your web browser at:
   ```
   http://localhost:3000
   ```

## Testing

To run the automated end-to-end integration test suite:
```bash
node test_workflow.js
```