You could have downloaded FFTea 1.0 for Mac from our software library for free. This free Mac app is a product of Curasi.
From the developer:
Design, Simulate and Export Linear FIR Filters for both Fixed-rate and Multirate Systems.
Digital filter design is fundamental in the design of Field Programmable Gate Array (FPGA) logic that utilizes digital signal processing techniques. Regardless of whether the filter is fixed-rate or multi-rate, there exists a need to easily design a linear phase filter and simulate its frequency response prior to implementation in an FPGA.