BACKGROUND AND OBJECTIVES: Many aspects of CKD management rely heavily on patient self-care, including medication and dietary adherence, self-monitoring of BP, and daily physical activity. Growing evidence suggests that incorporating smartphone-based applications can support self-care in CKD and chronic disease more generally. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We identified applications targeting patients with CKD by conducting a search of the US Apple App Store (iOS) and Google Play Store (Android) using the following four phrases: "kidney disease," "renal," "dialysis," and "kidney transplant." We considered the first 50 applications for each search term on each application store. We adapted a previously described framework for assessment of mobile health applications to account for kidney disease-specific content areas and evaluated applications on their types of patient engagement, quality, usability, and safety. Engagement and quality were assessed by both a patient and a nephrologist, usability was assessed by a patient, and safety was assessed by a nephrologist. Overall, two patients with CKD and three nephrologists performed the evaluations. We examined pairwise correlations between patient, nephrologist, and consumer ratings of application quality. RESULTS: Our search strategy identified 174 unique applications on Android and 165 unique applications on iOS. After excluding applications that were not related to kidney disease, were not patient facing, or were last updated before 2014, 12 Android-only applications, 11 iOS-only applications, and five dual-platform applications remained. Patient and nephrologist application quality ratings, assessed by the net promoter score, were not correlated (r=0.36; P=0.06). Consumer ratings on the application stores did not correlate with patient ratings of application quality (r=0.34; P=0.18). CONCLUSIONS: Only a small subset of CKD applications was highly rated by both patients and nephrologists. Patients' impressions of application quality are not directly linked to consumer application ratings or nephrologist impressions.