Low-latency interactive user interface

Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for a low latency interactive user interface. In one aspect, a method includes while individual characters in a sequence of characters are being entered into a field of an interactive user interface and before the sequence has been completely entered parsing the entered characters using a string pattern and presenting the parsed characters in a second field according to a presentation format. The method also includes sending one or more of the entered characters to a server. The method also includes receiving a different second string pattern and a different second presentation format from the server in response to the sending. The method also includes parsing one or more second entered characters using the second string pattern and presenting the parsed second entered characters in the second field according to a second presentation format.