This technical tip allows developers how to protect a Excel workbook from unauthorized access using Saaspose.Cells REST API in Java applications. Some important steps for performing this task is to build URI to Protect Workbook, sign URI, serialize the JSON request content, Represents Protection Types and use Protection Class above to apply the protection. Saaspose.Cells is a REST API for processing spreadsheets in the cloud. It allows creating, manipulating & converting spreadsheets in web, desktop, mobile & cloud applications. It supports rows, columns, cells, text, data, images, hyperlinks, comments, formulas & many other aspects of spreadsheets.