GridCraft
Open-source, clean-room spreadsheet (Microsoft Excel-style) in Rust
...It supports Microsoft Excel XLSX files as its native format, along with CSV and TSV files, and can import worksheet data from XLSB and ODS formats. GridCraft includes more than 500 spreadsheet functions, dynamic arrays, conditional formatting, data validation, sorting, filtering, and advanced calculation capabilities. The application also provides a command-line interface, JSON control channel, and Model Context Protocol (MCP) server that allow AI agents to create, modify, analyze, and automate spreadsheets. Available for Windows, macOS, Linux, FreeBSD, and web browsers, GridCraft operates without subscriptions or telemetry and is currently in alpha development.