Systems and methods for rule-based data stream processing by data collection, indexing, and visualization systems. An example method includes: receiving, by the computer system, an input data stream comprising raw machine data; processing the raw machine data by a data processing pipeline that produces transformed machine data, wherein the data processing pipeline comprises an ordered plurality of pipeline stages, wherein a pipeline stage of the ordered plurality of pipeline stages applies a rule of a set of rules to an input of the pipeline stage, wherein the rule specifies an action to be performed on the input of the pipeline stage responsive to evaluating a conditional expression applied to the input of the pipeline stage, wherein the action generates an output of the pipeline stage, and wherein the rule is selected based on a source type associated with the input data stream; and supplying the transformed machine data to a data collection, indexing, and visualization system.