An analysis of Rust usage in Windows 11 reveals multiple components built partially or entirely in Rust, including two servicing DLLs (CloudRecoveryDownloadTool.dll and UdiApiClient.dll), DWriteCore at 57.9% Rust, and the MathCAT library used by Narrator. Microsoft has developed an internal Rust toolchain with a UTC backend alternative to LLVM, announced in September 2026 as a Tier-1 language at the company.