PurposeThe benefits of physical activity for cancer survivors are increasingly recognised and smartphone applications are available to assist them to become more physically active. Cancer clinicians, however, lack confidence about which physical activity apps to recommend as evidence on their quality and content is limited. Therefore, we reviewed freely available commercial physical activity/fitness apps to systematically assess their behavioural change content and quality of their design.MethodsSystematic searches of the app stores for Apple and Android operating systems were conducted and apps were screened to identify free apps appropriate for cancer survivors. Quality was assessed using the Mobile App Rating Scale (MARS) and behavioural content was evaluated using the Behavioural Change Techniques Taxonomy (BCTT).ResultsOf 341 apps identified, 67 were judged appropriate for cancer survivors and 46% combined aerobic and strength/stretching content. The overall number of behavioural change techniques (BCT) included was 3.96 (SD=2.09), with the most frequent being feedback on behaviour' and goal setting behaviour'. The mean scores for objective and subjective quality were 4.11 (SD=0.59) and 3.07 (SD=0.91) respectively (range 0 to 5). Finally, a modest positive correlation was found between the number of BCT and the quality of engagement, awareness and knowledge as assessed by the MARS.ConclusionOnly a fifth of retrieved physical activity apps contained potentially suitable content for people affected by cancer. Overall, most apps we reviewed appeared to perform well in terms of their objective quality, but less well at promoting knowledge and awareness or help seeking related to physical activity.Implications for Cancer SurvivorsMany physical activity apps are available but the combined use of MARS and BCTT suggests that not all of them are suitable to the needs is a promising and feasible approach for assessing the applicability, usability and content of physical activity of apps employed by cancer survivors and this study is a first step toward developing a guide.