Ni-based superalloys are central to aero engines, power generation, and other demanding applications due to their high strength and corrosion resistance at elevated temperatures. At the same time, they are difficult to process—especially in welding and additive manufacturing (AM)—where several cracking phenomena limit performance. This review surveys research since 2015 and highlights failure mechanisms such as solidification cracking, liquation cracking, ductility dip cracking, and strain-age cracking, together with recent work on residual stresses and repair. A bibliometric overview is included to show research growth, leading countries, and affiliations. Key similarities and differences between welding and AM are discussed, with emphasis on how steeper gradients and faster cooling in AM shift cracking behavior relative to conventional welds. Weldability and processability test methods are summarized (e.g., Varestraint, hot-ductility, in-situ monitoring, and microstructural characterization). Particular attention is given to alloy chemistry, filler design, and pre-/post-heating strategies as crack-mitigation measures. Cracking mechanisms are then reviewed for both welding and AM, including recent results on new alloys and compositional adjustments. Finally, practical strategies and open challenges are summarized, followed by a brief outlook on process optimization, alloy tailoring, and the role of monitoring.