Challenge-dynamic credential pairs for client/server request validation

A server system programmed to validate requests from a client computer, the system comprising:

• one or more processors;
• one or more non-transitory computer-readable media storing instructions which, when executed by the one or more processors, cause:
• generating, at the server system, a first challenge credential to be sent to the client computer;
• rendering one or more first dynamic-credential instructions based on the first challenge credential, which when executed by the client computer, cause the client computer to generate a first dynamic credential that corresponds to the first challenge credential, to update the first dynamic credential one or more times, and to include the updated first dynamic credential in one or more first requests from the client computer;
• generating a first set of instructions including the first challenge credential and the one or more first dynamic-credential instructions, wherein the first set of instructions, when executed by the client computer, cause the first challenge credential to be included in the one or more first requests sent from the client computer;
• sending the first set of instructions to the client computer;
• receiving a request for data from the client computer;
• determining, based on the request, whether the client computer is a bot.