Abstract. Falsehoods continue to spread faster than facts in today’s age of continuous, digital connections. Recent studies show older adults engage more frequently with misinformation than younger users. Given the reported uptake of mobile technologies among older adults (61% of US adults over 65 owned a smartphone in 2021), much of these engagements may occur via smartphones or tablets. What types of fact-checkers are currently available on smartphones? How do older adults fact-check information they encounter in their daily lives? In this paper, we explore these questions with a systematic app review and a semi-structured interview with older adults. Among the 8372 unique smartphone fact-checking apps identified, 45 apps were qualitatively and systematically reviewed. Five distinct user interface (UI) elements emerged: news feed, article view, fact-checking widget, learning tool, and search view. An interactive fact-checking option was found in 73% of the apps. None of our older interviewees reported using a smartphone fact-checking app but described other fact-checking behaviors, such as asking friends or acquaintances with domain expertise or searching on Google.