📊 Cello - Terminal Spreadsheet Editor

A beautiful, fast, and feature-rich terminal-based Excel and CSV editor with vim-style keybindings and formula support.

✨ Features

✨ AI Formula Generation (NEW!)

Don't know the formula syntax? Just describe what you want in plain English:

• Press Ctrl+K to open AI Formula Generator
• Type: "Sum of column A" → Gets =SUM(A:A)
• Type: "Average of B1 to B10" → Gets =AVERAGE(B1:B10)
• Type: "Extract domain from email in A1" → Gets the right formula!
• Press Tab to insert the generated formula

Multiple AI Providers Supported:

• Gemini (Google)
• OpenAI (GPT-4, GPT-3.5)
• Claude (Anthropic)
• Mistral
• OpenRouter (access any model)

Press Ctrl+, to open configuration and set your preferred provider and API key.

Configuration: Run cello config to set up your AI provider and API key.

🧹 Smart Data Cleaning (NEW!)

Messy data? Cello can help you clean it up instantly:

• Press Ctrl+B to open the Data Cleaning tool
• Trim Whitespace: Remove leading/trailing spaces
• Remove Duplicates: Eliminate duplicate rows
• Fix Numbers: Convert text-formatted numbers to actual numbers
• Preview Changes: See exactly what will happen before you apply

📐 Powerful Formula Engine

Arithmetic: =A1+B1, =C1*2, =D1/E1-F1

15+ Built-in Functions:

• SUM(A1:A10) - Sum range
• AVERAGE(B1:B20) / AVG(...) - Average values
• COUNT(C1:C50) - Count numbers
• MAX(D1:D100) / MIN(...) - Find max/min
• IF(A1>100, "High", "Low") - Conditional logic
• CONCATENATE(A1, " ", B1) / CONCAT(...) - Join text
• UPPER(A1) / LOWER(A1) - Change case
• LEN(A1) - Text length
• ROUND(A1, 2) - Round numbers
• ABS(A1) - Absolute value
• SQRT(A1) - Square root
• POWER(2, 8) / POW(...) - Exponentiation

Auto-recalculation when cells change

✏️ Full Editing Capabilities

• Edit cells with formulas and values
• Insert/delete rows and columns
• Copy/paste single cells or ranges
• Fill down/right for quick data entry
• Apply formulas to entire ranges with automatic reference adjustment
• Auto-save with modification tracking
• Undo-friendly workflow with clear status messages

📊 Live Data Visualization

• Bar charts - Compare values visually
• Line charts - Show trends over time
• Sparklines - Compact inline charts
• Pie charts - Display proportions

How to use:

1. Press V to start range selection
2. Move cursor and press V again
3. Press v to open visualization
4. Press 1-4 to switch chart types

🔍 Powerful Navigation

• Vim-style keybindings (hjkl) and arrow keys
• Jump to cell (Ctrl+G) - supports A100, 500, or 10,5 formats
• Search (/) across cells and formulas
• Navigate results (n/N)
• Page Up/Down, Home/End
• Multi-sheet support with Tab navigation

📋 Data Operations

• Copy cell (c) or entire row (C)
• Paste (p) with multi-cell support
• Export to CSV or JSON
• Save (Ctrl+S) with format preservation
• Save As (Ctrl+Shift+S) to new file
• Toggle formula display (f)
• View cell details (Enter)
• Column Resizing (< / >)
• Data Cleaning (Ctrl+B)

� File Support

• Excel files (.xlsx, .xlsm, .xls) with formula preservation
• CSV files with formula support (saved as text)
• Multiple sheets with easy navigation
• Large file optimization with lazy loading
• Safe saving with backup on errors

🎨 Ten Beautiful Themes

Dark Themes:

• Catppuccin Mocha - Soft pastels, perfect for all-day use
• Nord - Cool Arctic blues, minimal and focused
• Rosé Pine - Elegant rose tones, sophisticated
• Tokyo Night - Vibrant cyberpunk aesthetic
• Gruvbox - Warm retro colors, comfortable
• Dracula - Classic high contrast theme

Light Themes:

• Catppuccin Latte - Gentle pastel light theme
• Solarized Light - Balanced contrast
• GitHub Light - Clean and minimal
• One Light - Soft Atom-inspired colors

🚀 Installation

Using Homebrew (macOS/Linux)

brew install SreeAditya-Dev/tap/cello

Using go install

go install github.com/SreeAditya-Dev/cello-tui@latest

Download Binary

Download pre-built binaries from the releases page.

Available for:

• macOS (Intel & Apple Silicon)
• Linux (x64 & ARM64)
• Windows (x64)

Build from Source

# Clone the repository
git clone https://github.com/SreeAditya-Dev/cello-tui.git
cd cello-tui

# Install dependencies
go mod download

# Build
go build -o cello .

# Optional: Install globally
sudo mv cello /usr/local/bin/

📖 Usage

# View a file (read-only until you press 'i')
cello data.xlsx

# Start with a specific theme
cello report.csv --theme nord

# Create new file (will be created on first save)
cello newfile.xlsx

⌨️ Keyboard Shortcuts

Navigation

• ↑↓←→ or hjkl - Navigate cells
• Page Up/Down or Ctrl+U/D - Scroll by page
• Home/End or 0/$ - First/last column
• g/G - First/last column
• Tab/Shift+Tab - Next/previous sheet
• Ctrl+G - Jump to specific cell

Editing

• i - Enter edit mode
• Enter - Commit changes (in edit) / View details (in normal)
• Tab - Save and move right (in edit mode)
• Shift+Tab - Save and move left (in edit mode)
• Esc - Cancel editing
• x - Delete cell content
• dd - Delete current row
• dc - Delete current column

Cell Operations

• c - Copy cell
• C - Copy entire row
• p - Paste
• o - Insert row below
• O - Insert column right
• Ctrl+J - Fill down (requires selection)
• Ctrl+L - Fill right (requires selection)
• Ctrl+A - Apply formula to range (requires selection)
• < / > - Decrease / Increase column width
• Ctrl+B - Clean data (trim whitespace)

File Operations

• Ctrl+S - Save file
• Ctrl+Shift+S - Save as
• e - Export to CSV/JSON
• q - Quit (press twice if unsaved changes)

Search & Navigation

• / - Search
• n/N - Next/previous search result
• Esc - Clear search

Visualization & Display

• V - Start/finish range selection
• v - Open visualization (after selection)
• 1-4 - Switch chart types (in viz mode)
• f - Toggle formula display
• t - Change theme
• ? - Toggle help
• Ctrl+K - AI Formula Generator
• Ctrl+, - Configure AI Providers

💡 Quick Start Guide

Viewing a File

cello mydata.xlsx
# Navigate with arrow keys or hjkl
# Press 'f' to toggle formula view
# Press 't' to change theme

Editing Data

# 1. Open file
cello mydata.xlsx

# 2. Navigate to a cell
# 3. Press 'i' to edit
# 4. Type value or formula: =SUM(A1:A10)
# 5. Press Enter to save
# 6. Press Ctrl+S to save file

Working with Formulas

# Create a formula
Press 'i' on cell C1
Type: =A1+B1
Press Enter

# Apply to entire column
Press 'V' to start selection at C1
Move to C10 and press 'V'
Move back to C1
Press Ctrl+A to apply formula
# Result: C1=A1+B1, C2=A2+B2, C3=A3+B3, etc.

Bulk Data Entry

Press 'i' to start editing
Type value and press Tab
Continue typing in next cell
Press Tab to keep moving right
Press Ctrl+S when done

🏗️ Project Structure

cello-tui/
├── main.go                    # Application entry point
├── internal/
│   ├── app/
│   │   ├── model.go          # State management
│   │   ├── update.go         # Event handling
│   │   ├── view.go           # Rendering logic
│   │   ├── keys.go           # Keybindings
│   │   ├── edit.go           # Edit operations
│   │   └── formulas.go       # Formula evaluation engine
│   ├── loader/
│   │   ├── loader.go         # File loading
│   │   └── save.go           # File saving
│   ├── theme/
│   │   └── theme.go          # Theme definitions
│   └── ui/
│       └── ui.go             # UI utilities
└── pkg/
    └── models/
        └── models.go         # Data models

🤝 Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

Development Setup

git clone https://github.com/SreeAditya-Dev/cello-tui.git
cd cello-tui

# Install dependencies
make deps

# Run tests
make test

# Build
make build

# Run with sample data
make run

Code Style

• Run make fmt before committing
• Follow Effective Go guidelines
• Add tests for new features
• Update documentation

📊 Examples

Sales Report with Formulas

     A        B        C          D
1  Item     Price    Qty      Total
2  Apples   1.50     10      =B2*C2
3  Oranges  2.00     5       =B3*C3
4  Total    -        -       =SUM(D2:D3)

Select D2:D4, cursor on D2, press Ctrl+A to apply formula pattern.

Conditional Formatting (Formula-based)

     A           B
1  Score    Grade
2  85       =IF(A2>=90,"A",IF(A2>=80,"B","C"))

Apply to B2:B20 with Ctrl+A for instant grading.

Data Summary

     A              B
1  Sales         1000
2  Costs          600
3  Profit      =A1-A2
4  Margin      =ROUND(A3/A1*100,2)

🔧 Advanced Features

Formula Auto-adjustment

When you apply a formula to a range, cell references automatically adjust:

Source: A1 contains =B1+C1

Apply to A1:A5:
  A1: =B1+C1
  A2: =B2+C2
  A3: =B3+C3
  A4: =B4+C4
  A5: =B5+C5

Multi-cell Paste

Copy ranges from other apps and paste into Cello:

• Tab-separated values paste as multiple columns
• Newline-separated values paste as multiple rows
• Formulas (starting with =) are preserved

Keyboard-driven Workflow

i          Enter edit mode
Type data
Tab        Save and move to next cell
Tab        Continue entering data
Tab        Keep going...
Ctrl+S     Save entire file

📄 License

This project is licensed under the MIT License - see the LICENSE file for details.

🙏 Acknowledgments

• Built with Bubble Tea TUI framework
• Styled with Lipgloss
• Excel parsing by Excelize
• Clipboard by atotto/clipboard
• Themes inspired by Catppuccin, Nord, Rosé Pine, and others

🔒 Security

If you discover a security vulnerability, please create a private security advisory on GitHub or email the maintainers.

📮 Contact

• GitHub: @SreeAditya-Dev
• Issues: GitHub Issues
• Discussions: GitHub Discussions

⭐ Star History

If you find Cello useful, please consider giving it a star on GitHub!

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Made with ❤️ for terminal enthusiasts and spreadsheet power users everywhere.