Kepler is a free software system for designing, executing, reusing, evolving, archiving, and sharing scientific workflows.

The Kepler system principally targets the use of a workflow metaphor for organizing computational tasks that are directed towards particular scientific analysis and modeling goals.

For example, Kepler provides access to data stored in the Knowledge Network for Biocomplexity (KNB) Metacat server[6] and described using Ecological Metadata Language.

Provenance is a critical concept in scientific workflows, since it allows scientists to understand the origin of their results, to repeat their experiments, and to validate the processes that were used to derive data products.

[8] In order for a workflow to be reproduced, provenance information must be recorded that indicates where the data originated, how it was altered, and which components and what parameter settings were used.

[9] Little support exists in current systems to allow end-users to query provenance information in scientifically meaningful ways, in particular when advanced workflow execution models go beyond simple DAGs (as in process networks).