Variegate is a source code diversification tool that addresses IT monoculture vulnerabilities by creating multiple functionally equivalent versions of software with varied attack surfaces. The tool takes an original program and test suite as input and produces a set of program variants that maintain functionality while achieving binary diversity. Variegate operates by applying mutations to source code, ranging from simple code deletions to complex structured refactorings such as variable or function inlining or extraction. The tool validates that mutations do not affect program functionality by verifying that transformed programs behave correctly against the provided test suite. When an extensive test suite is not available, Variegate can be restricted to safe, functionality-preserving mutations that mimic refactoring code changes. This approach creates a population of correct program versions that reduce the risk of widespread exploitation, as malware attacks that succeed on one instance may fail against diversified variants. The tool was developed with support from the Navy, Office of Naval Research, and DARPA under contracts N68335-17-C-0700 and D17PC00096.