Multimodal interfaces combining speech, graphics, and sensor input are becoming increasingly important for interaction with the rapidly expanding variety of nontraditional platforms, including mobile, items in the Internet of Things, wearables, and robots. While speech technologies on the Open Web Platform are still in their early stages, standards like WebRTC, WebAudio, and Web Sockets are providing the audio handling support required by speech applications. This session demonstrates how to develop multimodal clients using the Open Web Platform and discusses integration with cloud resources for technologies such as speech recognition and natural language understanding. Attendees should have access to a browser that supports the Open Web Platform standards such as the current versions of Chrome, Firefox, or Opera. We cover the following topics: motivation for multimodal applications (demos and sample applications); graphical multimodal tools (HTML5, JavaScript, and CSS); speech tools in the browser (audio standards and speech APIs); cloud processing (speech and natural language processing services); and building a multimodal application.