Here, dspGuru catalogs DSP-related software tools. By "tools" we mean "software you use to develop a DSP system.
Filter Design Tools - Virtually every DSP system has at least one IIR or FIR filter, so digital filter design is the first thing. Although digital filters can sometimes be designed manually, a good filter design program is part of nearly every DSP designer's basic toolkit.
Software Development Tools - If your DSP system is implemented in software, you will need software development tools including as assemblers, compilers, and linkers. In many cases, these tools are provided by the manufacturers of the microprocessor they target. However, tools also are available from third-parties and even as OpenDSP software.
System Simulation Tools - System simulation tools ("math" programs) are primarily useful for designing the architecture of your DSP system. They let you quickly prototype your DSP system so you can efficiently experiment with different architectural ideas. Some are matrix-based programming languages, and others are graphical systems which allow you to connect high-level DSP blocks. They all provide powerful built-in DSP functions so you can work at a very high level of abstraction.