Résumé : Background: Bone age in children is mainly assessed using the Greulich and Pyle (GP) atlas, a validated method with limited interobserver accuracy. While automated methods increase interobserver accuracy, they represent considerable costs and technical requirements. Objective: A proof-of-concept study to create and evaluate an online software program, Boneureka©, based on linear metacarpal length measurements, to assess bone age in healthy children. Materials and methods: The study retrospectively included 434 consecutive children (215 girls) who underwent a left-hand radiograph to rule out trauma between March 2008 and December 2017. Two reviewers measured the second to fourth metacarpal lengths on each radiograph and the distance between the centre of the epiphyses of the second and fifth metacarpals. A single reviewer estimated the bone age using the GP atlas. The automated software assessed the bone age for all radiographs. A mathematical model was developed based on linear regressions to provide the mean bone age and standard deviation based on the estimates. Pearson and intraclass correlation coefficient (ICC) were used to evaluate the correlation and agreement between the estimated bone ages using Boneureka©, the GP atlas and BoneXpert® compared to chronological age. Results: The measure that showed the highest correlation (r2=0.877 for girls and r2=0.834 for boys; P<.001) and the highest ICC (ICC=0.937 for girls and ICC=0.926 for boys; P<0.001) with chronological age was length of the second metacarpal. The GP atlas and the automated software evaluation had excellent ICC with chronological age (ICC>0.95 for both methods and sexes). Using this data, we created an online software program based on the second metacarpal length to obtain bone age estimates, means and standard deviations. Conclusion: The newly created online software Boneureka,© based on the second metacarpal length, is a reliable and user-friendly tool to assess bone age in healthy children. Further studies on a larger population should be performed to validate the developed reference values.