SDS (siRNA Design Software) is a software tool that helps to design siRNAs for silencing gene expression. The tool takes an mRNA sequence and makes use of existing design tools to output a set of candidates. These candidates are then filtered based on the secondary structure. With the following features: It provides a unified platform for using existing software. It compares the output of existing software. It enhances the existing software by filtering ineffective siRNAs based on secondary structure. Registration not required.