Unregulated sympathetic activity due to stress poses a risk for various physical and mental health issues such as chronic fatigue, asthma, obesity, disorientation, and gastrointestinal conditions. Despite the abundance of stress regulation tools for adults, there is a noticeable gap in child-friendly tools that empower children with self-monitoring and stress management techniques. Various methods have been developed to help adults and some short-term experiments have been conducted with children to alleviate stress levels, but there are no current approaches that aim to both observe and help children in the long-term. Additionally, the research and concrete applications lack accessibility with high cost or closed-source, creating an insufficient benefit. To address this gap, we propose OxPal, a child-friendly biofeedback device and an accompanying application, designed to reduce sympathetic activity by regulating breathing patterns. OxPal, a ball-shaped biofeedback product, tracks the Heart Rate Variability (HRV) data by using a photoplethysmography (PPG) sensor that measures blood volume changes. PPG is a non-invasive and cost-effective sensor that allows monitoring of respiration rate and blood pressure. By using the PPG sensor, we are able to collect the HRV data, which is used as an indicator of stress levels. OxPal’s complementing application interprets the data, informs personalized and effective breathing techniques in a child-friendly approach, and encourages children to regulate their own breathing and manage their stress levels. There are numerous breathing techniques that can be used to regulate breathing and manage stress levels, but some of the most research-based and reliable techniques have been found to be pranayama breathing. Crucially, OxPal is also openly sourced, and non-commercial, ensuring accessibility for all children. Committed to enhancing the well-being of every child, our research and application aspire to provide the necessary tools that can be easily incorporated into daily life, and promote a healthy and balanced lifestyle.