Wessa.net offers these software applications free of charge:

 
Descriptive Statistics SoftwareThis collection of Free Statistics Calculators offers a wide range of descriptive and explorative types of statistical measures and analysis: Central Tendency, Average, Mean, Median, Variability, Interquartile Range, Concentration, Lorenz Curve, Gini Coefficient, Skewness, Kurtosis, Quartiles, Percentiles, Notched Boxplot, Histogram, Correlation, Partial Correlation, Rank Correlation (Spearman and Kendall), Simple Regression, Kernel Density Estimation, Harrell-Davis Quantiles, Bivariate KDE, Correlation Matrix, Stem-and-leaf plot, Explorative Data Analysis
 
Regression SoftwareThis is a collection of Regression-based types of analysis for single and multiple equations: Multiple Regression Equations, Bias-Reduced Logistic Regression (Firth method), Recursive Partitioning (Classification & Regression Trees), Variance-based Structural Equation Modeling (Partial Least Squares - Path Modeling).
 
Statistical DistributionsFeatures Random Number Generators, PPCC Plots (incl. Tukey lambda), and Statistical Distribution Fitting Modules (Maximum Likelihood) for a series of important distributions: Beta, Inverted Beta, Cauchy 1, Cauchy (2 parameters), Chi, Chi Square (1 parameter), Chi Square (2 parameters), Erlang, Exponential, Fisher F, Gamma, Inverted Gamma, Gumbel, Laplace, Logistic, Lognormal, Normal, Pareto, Power, Rayleigh, r-Distribution, Rectangular (Uniform), Student t, Triangular, and Weibull.
 
Statistical Hypothesis Testing SoftwareOffers statistical testing of a variety of hypotheses: Population Mean, Mean (critical value, p-value, type II error, sample size), Skewness/Kurtosis, Quasi Random-Walk
 
Time Series Analysis (R modules)Performs Univariate Box-Jenkins ARIMA modeling, forecasting, and residual model checking. In future this module will replace the old versions based on C code.
 
Statistics Education at Simon Fraser University

This section contains various types of Statistics Software for Statistics Education that have been created by Larry Weldon at Simon Fraser University, Vancouver, Canada.
 
Statistics Education at Aston University

This section contains various types of Statistics Software for Statistics Education that have been created by Ian Holliday at Aston University, Birmingham, UK.
 

Sample Size Software(sample size, sample accuracy, confidence interval)
 
Factor Analysis(Factor Analysis, Principal Components)
 
Clustering Software(Agglomerative Nesting, Hierarchical Clustering)