FFT Page
- Links and various Fortran FFT implementations.
- http://faculty.prairiestate.edu/skifowit/fft/

Sigview - FFT Analysis Software
- A real-time spectral analysis application with spectral analysis tools, statistical functions and visualization system. It can analyse data from WAV files or sound input from microphone or CD player. Shareware.
- http://www.sigview.com/

Row-oriented Multidimensional Fast Transform Library (RMFTL)
- Power-of-two real and complex FFT software that is faster, and more accurate, than conventional iterative implementation of one-dimensional FFTs. Based on a propietary algorithm.
- http://www.davis-inc.com/rmftl

fftpack
- A package of Fortran subprograms for the fast Fourier transform of periodic and other symmetric sequences.
- http://www.netlib.org/fftpack/

Jens J. Nielsen's Home Page
- Arbitrary length FFT C-source, 3D gravity simulator, quantization of FIR filter coefficients. C source.
- http://home.get2net.dk/jjn

FFTW
- Fast free C FFT library; includes multi-dimensional, real-complex, and parallel transforms.
- http://www.fftw.org/

Joerg's FXT Page
- Source code and links for many different FFT implementations and related information.
- http://www.jjj.de/fxt/