This technical report describes the current state of the Web Speech API, which provides a JavaScript interface for speech analysis and speech synthesis to web applications. The focus lies on measuring the performance of Google's speech recognition web service that is behind the experimental API implementation in the Chromium browser. To this end, sentence correctness and word accuracy is measured using the TSP speech database with more than 1400 recordings of the Harvard sentences. The report also puts the Web Speech API into historical context and speculates about future prospects. A practical use- case is given that demonstrates how the API can be used in a web application. Supplemental data and the use-case is published online.