The repository has been moved to: https://github.com/wojdyr/fityk. Fityk is nonlinear curve-fitting and data analysis software. It is specialized in fitting peaks (bell-shaped functions like Gaussian, Loretzian, Pearson7, Voigt) to experimental data.
Clean written and very useful general purpose tool with X-ray roots and extension. Nice script language giving a lot of power to users who need to work on similar data a lot. Lately did index and pre-evaluate 400+ X-Ray profiles in minutes. Thanks to bash and fityk.