About 60% of babies born after 36 weeks of pregnancy have jaundice during the first two weeks of life. Due to the accumulation of bilirubin in the bloodstream, jaundiced babies appear yellow, which allows healthcare professionals to visually identify significantly jaundiced babies. They will be referred for a blood test to determine if the bilirubin level is so high that treatment such as phototherapy, or more intensive help is required. Left untreated or treatment delayed, jaundice can potentially result in serious brain damage and even death (rare). However, visual inspection of jaundiced babies is inaccurate, often need to unnecessary referrals to hospital blood tests. We have developed the neoSCB smartphone app, which accurately detects significant jaundice by taking photographs of the baby's sclera (white part of an eye) and analysing its yellowness using a diagnostic algorithm. The neoSCB app has previously been validated in Ghana involving over 700 newborn babies. In this new study, we will recruit 405 newborn babies with a range of jaundice levels to validate an optimised diagnostic algorithm following our latest research. Two existing commercial screening devices will also be used to investigate whether the app delivers a similar accuracy, at a fraction of the cost. We will enhance the usability of the app and add new features following feedback from patients and healthcare professionals. A health economic study will be conducted to evaluate the economic benefits to the NHS.