Debugging for integrated scripting applications

Methods, systems, and apparatus, including computer programs encoded on computer storage media, for implementing a debugger for integrated scripting applications. One of the methods includes generating a modified script from an original script, the modified script being written in a scripting language and having a respective breakpoint inquiry command for a plurality of original commands from the original script, wherein each breakpoint inquiry command calls a breakpoint inquiry function with a unique identifier assigned to a corresponding original command. The modified script is executed including calling the breakpoint inquiry function before the plurality of original commands from the original script. If a particular call to the breakpoint inquiry function corresponds to a set breakpoint, execution of the modified script is stopped and updated debugging information is provided to a debug client configured to generate a user interface presentation of the updated debugging information.