This study explores the Health Code (Chinese: 健康码), a digital contact tracing application used in Mainland China during the COVID-19 pandemic, and examines the process and impact of its entry into users’ lives and gradual infrastructuralisation within the field of internet infrastructure research. Results show that techno-nationalism was the basis for the inception, implementation, and development of the Health Code. Furthermore, the Health Code has gradually transformed from an early digital health credential into a type of ‘access infrastructure’ by linking physical, information, and communication infrastructure. As access infrastructure, the relationship between the Health Code and users was a tense one, with users actively engaging in ‘micro-help’ on social media platforms and performing ‘soft-resistance’ on psychological and operational levels. Concurrently, the Health Code was embedded into users’ usage habits and social culture, becoming a shared memory and potential digital infrastructure for the future.