Using instrumentation code to detect bots or malware

A computer system comprising:

• one or more hardware processors;
• a memory coupled to the one or more hardware processors and storing one or more instructions which, when executed by the one or more hardware processors, cause the one or more hardware processors to:
• obtain data corresponding to requests from a plurality of client devices for a web resource comprising web code, wherein the web resource is hosted by a first web server system;
• for a first client device of the plurality of client devices, serve instrumentation code that is configured to execute on the first client device to monitor execution of the web code of the web resource at the first client device;
• receive, from the first client device, one or more responses generated by the instrumentation code at the first client device based one or more interactions with the web code at the first client device.