HClib is a task-based parallel programming model that supports the finish-async, parallel-for, and future-promise parallel programming patterns through both C and C++ APIs. HClib explicitly exposes hardware locality of the hardware, while allowing the programmer to fall back on sane defaults. The HClib runtime is a lightweight, work-stealing, and locality-aware runtime. HClib is not itself an exascale programming system, but is intended to be the intra-node resource management and scheduling component within an exascale programming system, integrating with inter-node communication models such as MPI, UPC++, or OpenSHMEM.