Recognizing the role that online platforms hold in education, this study explores how three early career elementary teachers perceive the affordances and constraints of online curriculum sharing platforms. Using pedagogical design capacity as a theoretical framework, we engaged in a comparative qualitative case study to examine the ways early career teachers in differing contexts approach platforms like TeachersPayTeachers and Instagram. Findings emphasize the participants' perceived affordances and constraints of these platforms and the curricular materials found in these spaces. Additionally, we identify three distinct points of interest for the teaching profession and future research to better understand teachers' use of these platforms and the application of their pedagogical design capacity when working to supplement and design curriculum.