Systems for computer code development and maintenance. Embodiments select one or more sections of source code, then modify the sections of source code by adding marker code where the marker code is executed when respective marked source code is executed. The marked source code is deployed, and a logging facility receives log messages responsive to the execution of marked source code. A comparison facility is used to identify active code based on the receipt of the log messages. A service can be invoked to remove marker code from the active code identified by one or more log messages. Remaining marked code can be deemed as inactive suspects. Additional steps can process the inactive suspects to identify inactive or “dead code” code based on expiration of a time period during which the “dead code” did not emit any log messages. A further step can remove “dead code” from a code base.