Development effort: Even though these frameworks in theory facilitate “Build Once and Deploy on Multiple Devices”, in practice apps require tweaking for each platform. Typically, plan on 20-25% additional effort on each platform once the base app is built. Some device functions may already be supported by the cross-platform framework, so a careful analysis is needed to determine what additional effort is required when developing on multiple platforms. Most cross-platform frameworks let you build plug-ins for device features not supported by the platform itself. However, plug-ins need to be written for each platform, which adds to the overall effort.