Application development and delivery (AD&D) leaders shifting to modern application development are like acrobats performing above a flimsy net. The tools and technologies they need to support the planning, execution, and evaluation of customer-focused applications just aren't widely available yet. The biggest gaps are in portfolio management, test-and-learn development environments, and digital application platforms. This report provides an overview of the tools and technologies needed to support AD&D leaders' business technology (BT) agenda. This is an update of a previously published report; Forrester reviews and updates it periodically for continued relevance and accuracy.