A computer system is configured to improve security of server computers interacting with client computers, and comprises: a memory, a processor coupled to the memory, and source code obfuscation logic coupled to the memory and the processor. The source code obfuscation logic is configured to read, from the memory, one or more original source code instructions that are configured to achieve an expected result when executed by a web browser on a client computer; to apply one or more obfuscation transformations, to the one or more original source code instructions, to produce one or more obfuscated source code instructions that are configured to achieve the same expected result when executed by the web browser but is expressed in an obfuscated format; to write the one or more obfuscated source code instructions to the memory.