In this paper, a new general form for the non–polynomial cubic spline function is introduced. This form enables us to generate about ten different formulas of the proposed spline function. Although some these functions have been used before to solve some types of differential and integral equations, the others are considered new. The ten functions are used to approximate the solution of linear, nonlinear and fuzzy Fredholm integral equations of second kind. Moreover, the convergence analysis of the proposed method is established which indicates that its order of convergence is four. Also, some examples are solved and compared with the previous methods which showed that the present method is more accurate.