Data file generated by Xilinx ISE, an application used for creating and testing electronic circuit designs; contains a Xilinx-specific "netlist," which includes the logical design data and constraints for the circuit; used for storing the constructed, or "synthesized," design, which can be passed on for design implementation (e.g., generating .NGD and .BIT files).

NGC files are generated using Xilinx Synthesis Technology (XST), an application included with the Xilinx ISE suite that synthesizes Hardware Description Language (HDL) designs into Xilinx-specific netlists. Example input HDL file format include Verilog (.V) files and VHDL (.VHD) files.