Previous research has shown that phonological awareness is one of the most important prerequisites for early reading. Monitoring its development requires reliable, easy-to-use instruments especially in the last years of kindergarten. The present study aims to explore the potential for assessing phonological awareness and some of its subskills through online testing. Participants of the study were 317 kindergarteners (M[subscript age] = 6.61, SD = 0.54 years). The instruments developed for this study within an online assessment platform in two assessment dimensions (syllable and phoneme awareness) contain nine subtests (syllable synthesis, segmentation, deletion; phoneme identification in different sound environments, identification of phoneme position, identification of initial phonemes, phoneme synthesis and segmentation). The results of the study show that: (1) the test is a reliable assessment tool for kindergarteners' phonological awareness skills; (2) according to the underlying measurement model of phonological awareness, the tasks are separated based on particular operational components independently of the size of the language element involved; (3) segmentation tasks proved to be the most difficult parts of the test; and (4) the media effect is insignificant. The online test aims to emphasize the importance of online testing and the inseparable relationship between measuring and developing phonological awareness, prompting teachers to rethink their teaching methods. It also introduces a new tool for educators to use, tailored to children's needs but potentially challenging for teachers with lower ICT literacy, requiring methodological support, ultimately providing a new opportunity for kindergartens.