Visible Vowels is a web app for the analysis of acoustic vowel measurements: f0, formants and duration. The app is an useful instrument for research in phonetics, sociolinguistics, dialectology, forensic linguistics, and speech-language pathology. The following people were involved in the development of Visible Vowels: Wilbert Heeringa (implementation), Hans Van de Velde (project manager), Vincent van Heuven (advice). Visible Vowels is still under development. Comments are welcome and can be sent to