The aim of this study was to assess the psychometric properties of the mobile application forward head posture in terms of validity, inter- and intra-rater reliability, minimum detectable change, sensitivity, and specificity to measure craniovertebral angle. In total, 44 subjects (mean age 23.30 ± 4.44 years) were evaluated in the standing position with markers on the tragus and cutaneous prominence of seventh cervical vertebra (C7). We had two experienced and trained physiotherapists assess cervical posture using the mobile application forward head posture and photogrammetry. Intraclass correlation coefficients were used to determine validity and reliability. A contingency table was made to determine sensitivity and specificity. Intra-rater reliability of the mobile application forward head posture had an intraclass correlation coefficient of 0.88. The inter-rater reliability generated an intraclass correlation coefficient of 0.83 to 0.89. Criterion validity data were above 0.82. The minimum detectable change was 4.96° for intra-rater and 5.52° for inter-rater reliability. The smartphone application exhibited 94.4% sensitivity and 84.6% specificity. The smartphone application forward head posture is a valid and reliable tool to measure craniovertebral angle in a standing position and, therefore, could be a useful assessment tool in clinical practice.