The persistent disparity between organ availability and demand has driven increasing interest in the transplantation of livers from donations after circulatory death. As these organs carry a higher risk of post-transplant complications due to the prolonged warm ischemia times, a comprehensive viability assessment is essential for optimal organ selection. Over the past years the assessment of these livers has advanced significantly, particularly by utilizing and refining the various machine perfusion protocols available. Each of these techniques, including both in situ strategies and ex situ strategies, has demonstrated distinct advantages in assessing graft viability and improving transplant outcomes. This chapter aims to explore the role and timing of these strategies in viability assessment. Currently available point-of-care biomarkers, ranging from well-established markers included in consensus guidelines to proposed thresholds based on recent pre-clinical research, are summarized. Emerging biomarkers in the fields of genomics, transcriptomics, and proteomics, along with currently explored assessment criteria for novel perfusion strategies such as long-term machine perfusion, are outlined. Still, viability assessment remains an evolving field, with key challenges that need to be addressed to further refine viability markers, and to safely expand currently proposed thresholds without compromising patient outcomes.