'Just In Time Design' is an important and useful concept for visual design that the NoPSD movement attempts to capture. You don't need to design the whole application or every UI element up front. Design things as you need them with as lightweight tools as you can use. We have seen a corresponding growth in simpler tools with faster learning curves, such as Sketch, as well as an increasing return to pen-and-paper (especially when paired with an existing robust digital style guide). Because of the limitations of flat mock-ups when you’re designing for screens, creating prototypes of varying fidelity with tools such as Invision, FramerJS and Origami - or simply HTML/CSS and a bit of JavaScript - has also become increasingly common and valuable for communicating design intent.
NoPSD is a movement to integrate design activities into the iterative feedback cycles required to build great software. The name aims to dislodge the PSD as the final canonical design artifact rather than taking a dig at the Adobe software. Instead of signing off on a pixel-perfect design specification at the start of a project, teams are urged to embrace Continuous Design: embedding designers into delivery teams, using lo-fi techniques for prototyping, and collaborating to refine the design in the target UI technology (normally HTML and CSS). This approach speeds responding to real user feedback, allows testing designs across multiple devices and form-factors, and embraces the dynamic nature of both digital products and the product creation process.
