1. A method comprising: accessing a particular page of Web application that includes an interactive form having at least one field for entry of data by a user of the Web application, the interactive form rendered by the Web application based on code for the interactive form; extracting input validation code from the code, the input validation code including at least one constraint on data entered into the at least one field; extracting the at least one constraint based on an analysis of the input validation code; solving, for the at least one field, for a string value based at least on the at least one constraint for the at least one field; automatically entering, into the at least one field, the string value; and automatically submitting the interactive form, including the string value entered into the at least one field.