Users are enabled to navigate a spreadsheet document presented by a web service in a similar fashion to a locally executed spreadsheet application by retrieving blocks of grid data asynchronously in order to display or refresh the area(s) of the spreadsheet currently being viewed by the user as the user navigates the spreadsheet grid or dynamic updates occur. The blocks are laid out in the browser's user interface to fill the user's viewport as well as a predefined buffer around the edge of the viewport. As such, when the user scrolls or updates occur, data associated with blocks are added, updated, or removed in the browser as required to fill the user's viewport.