Google Sheets - Synchronizing, online-based word processor, part of Google Drive.
EtherCalc - EtherCalc is a web spreadsheet.
Sheetgo - Connect spreadsheets. Automate your work.
Aspose.Cells for Cloud - Aspose.Cells for Cloud is a REST based API for processing spreadsheets in the cloud.
Simple Spreadsheet - Simple Spreadsheet
Excel Online - Excel Online, part of Office Online, is the online version of Microsoft Excel.