Limited attention has been paid to platforms in informal settlements, where residents face multiple, simultaneous resource constraints. We address this challenge by elucidating how informal settlement residents use platforms to address resource constraints and by identifying limitations to platform deployment. Conceptually, we combine literature on platforms and informal settlements with that on frugal innovation to distinguish various platform domains and introduce the concept of platform frugality to explain platform deployment. Based on an empirical case study of Mathare informal settlement, we reveal that platform frugality varies across domains. Social media and certain fintech platforms are more frugal than other platforms and are more widely deployed in informal settlements, addressing more resource constraints. More advanced fintech, gig, health, and utility platforms are rarely used in informal settlements. Generic limitations to platform deployment include costs and residents' lack of formal IDs.