The advent of HTML5 has sparked a great increase in interest in the web as a development platform for a variety of different research applications. Due to its ability to easily deploy software to remote clients and the recent development of standardized browser APIs, we argue that the browser has become a good platform to develop a speech labeling tool for. This paper introduces a preliminary version of an open-source client-side web application for labeling speech data, visualizing speech and segmentation information and manually correcting derived speech signals such as formant trajectories. The user interface has been designed to be as user-friendly as possible in order to make the sometimes tedious task of transcribing as easy and efficient as possible. The future integration into the next iteration of the EMU speech database management system and its general architecture will also be outlined, as the work presented here is only one of several components contributing to the future system.