Tag software is included in web applications to facilitate categorization and classification of information. Generally, freely available tag software is adapted or new code written to incorporate tagging. However, there is an absence of requirement and design document for tagging, even academically. It becomes difficult to know the features that can be included in tag software; also, not all features may be required. This chapter presents a framework for integration of tag software in web applications. The framework has four components corresponding to phases of the software development lifecycle. For requirement, a weighted requirement checklist is presented to ease requirement selection. A metric, software estimation, is defined for quantifying selected requirement. A logical design defined for design phase displays interaction of entities with users. For development, best mechanisms are suggested to web applications. Software engineering artefacts are provided to help during testing. A case study is presented where estimation and design is applied to freely available tag software.