OpenSheet

A fast, free, open-source editor for .xlsx and .csv on macOS and Windows. No Microsoft Excel, no account, no cloud.

Download · Features · Shortcuts · Build from source

Open a spreadsheet, fix it, clean up duplicates, save it. OpenSheet is a lightweight desktop app for everyday .xlsx and .csv work. It opens quickly, runs entirely on your computer, and never uploads your files.

Download

Get the latest build from Releases:

Platform	File
macOS, Apple Silicon (M1–M4)	OpenSheet-macOS-arm64.zip
macOS, Intel	OpenSheet-macOS-x64.zip
Windows 10/11 (64-bit)	OpenSheet-Windows-x64.zip

Everything is bundled, so you don't need to install .NET.

macOS says the app "can't be opened" or "is damaged"

The app isn't notarized by Apple yet. Move it to Applications, then either right-click it → Open → Open, or run:

xattr -dr com.apple.quarantine "/Applications/OpenSheet.app"

Windows shows "Windows protected your PC"

The exe isn't code-signed yet. Click More info → Run anyway.

Features

Editing

• Edit right in the cell: start typing, double-click, or press F2
• Formulas (=SUM(B:B), =D2*E2, …). While typing one, click or drag cells, column headers or row headers to insert the reference
• Undo / redo for everything, including deleted rows and sheets
• Cut, copy and paste ranges. Formulas shift like in Excel, and paste works with blocks copied from Excel or Google Sheets

Selecting and navigating

• Click or drag column and row headers to select whole columns or rows; drag or Shift+click to select ranges; Cmd/Ctrl+A for everything
• Cmd/Ctrl+Arrow jumps to the edge of the data; Find (Cmd/Ctrl+F) searches the sheet
• Right-click menus on cells, headers and sheet tabs

Cleaning data

• Find duplicates by one or more columns. Matching rows are highlighted, then you can delete them all, keep one of each, or copy or move them to a new sheet
• Insert and delete rows and columns. Formulas and hyperlinks follow

Sheets and files

• Opens and saves .xlsx and .csv. CSV files can use commas, semicolons or tabs. Thai and other non-English text works both ways, and CSVs are saved so Excel reads them correctly
• Add, rename (double-click the tab), duplicate, delete, and drag tabs to reorder sheets
• Drop another .xlsx or .csv onto the window to open it, import its sheets, or append its rows to the current sheet
• Open from Finder or Explorer, drag & drop, Save / Save As. The app asks before you lose unsaved changes

Keyboard shortcuts

Cmd on macOS, Ctrl on Windows.

Keys	Action
Cmd+O / Cmd+S / Cmd+Shift+S	Open / Save / Save As
Cmd+Z / Cmd+Shift+Z (or Cmd+Y)	Undo / Redo
Cmd+X / Cmd+C / Cmd+V	Cut / Copy / Paste
Delete or Backspace	Clear selection
Type, F2, or double-click	Edit cell
Enter / Tab (+Shift to go back)	Save the edit and move down / right
Esc	Cancel the edit or close a bar
Arrows, Page Up/Down, Home	Move
Cmd+Arrow	Jump to the edge of the data
Cmd+Home	Go to A1
Shift+Arrow, Shift+click, drag	Extend the selection
Cmd+A	Select all
Cmd+Page Down / Page Up	Next / previous sheet
Shift+F11	New sheet
Cmd+F, then Enter / Shift+Enter	Find next / previous

Build from source

Needs the .NET 10 SDK.

git clone https://github.com/thanakorn1999/opensheet.git
cd opensheet
dotnet run --project src/OpenSheet.App   # run it
dotnet test                               # run the tests

macOS app (publish/OpenSheet.app):

./build-mac.sh             # build for this Mac
./build-mac.sh --install   # build and copy to /Applications
RID=osx-x64 ./build-mac.sh # build for Intel Macs

To make it the default for .xlsx (or .csv), select one in Finder, press Cmd+I, set Open with to OpenSheet, then click Change All….

Windows exe (one file in publish/win; this also works when run from a Mac or Linux):

dotnet publish src/OpenSheet.App -c Release -r win-x64 --self-contained \
  -p:PublishSingleFile=true -p:IncludeNativeLibrariesForSelfExtract=true -o publish/win

The app icon is generated by python3 assets/make-icon.py (needs Pillow).

How it works

• src/OpenSheet.Core holds the workbook logic, with no UI. It wraps ClosedXML and handles undo, ranges, duplicates, import and CSV.
• src/OpenSheet.App is the Avalonia desktop app. The grid draws only the visible cells, so large sheets stay smooth.
• tests/OpenSheet.Core.Tests has the xUnit tests that run on every push.

Limitations

Not there yet:

• Formatting tools (bold, colors, number formats). Existing formatting is kept when you save
• Real column widths and row heights
• Charts, pivot tables and images. ClosedXML may not keep all of them when saving, so use Save As on files that have them

Issues and pull requests are welcome.

License

MIT. Avalonia and ClosedXML are MIT-licensed too.