XlsWork XLS editor for spreadsheets extension
Web browser extension that is a XLS and XLSX editor that lets you edit your spreadsheets directly on the web browser. App available in the Chrome web store and Firefox marketplace:
PDFOffice PDF editor online extension for Firefox and Chrome
PDFOffice is a PDF Editor online from which you can perform editing operations over PDF files but using your web browser. App available in the Chrome web store and Firefox marketplace:
OfficeWork Office Online extension for Firefox and Chrome
OfficeWork is an office online suite that provides a Document Editor, a Presentation Editor and Spreadsheet Editor. App available in the Chrome web store and Firefox marketplace: