The paper introduces REST (RESTing-state fMRI data analysis Toolkit), a MATLAB-based software package designed for the analysis of resting-state functional magnetic resonance imaging (RS-fMRI) data. REST is developed to address the lack of a publicly available, systematically integrated, and user-friendly tool for RS-fMRI data processing. It includes various analytic methods such as functional connectivity analysis, regional homogeneity (ReHo), amplitude of low-frequency fluctuation (ALFF), and fractional ALFF (fALFF). Additional functions include DICOM sorting, linear trend removal, bandpass filtering, time course extraction, regression of covariates, image calculation, and statistical analysis. REST is open-source and freely available at http://www.restfmri.net. The paper also provides a detailed description of the algorithms used in REST, including functional connectivity, ReHo, and ALFF, and demonstrates its usage through an example dataset. REST has been used in several recent publications and has been shown to be effective in analyzing RS-fMRI data.The paper introduces REST (RESTing-state fMRI data analysis Toolkit), a MATLAB-based software package designed for the analysis of resting-state functional magnetic resonance imaging (RS-fMRI) data. REST is developed to address the lack of a publicly available, systematically integrated, and user-friendly tool for RS-fMRI data processing. It includes various analytic methods such as functional connectivity analysis, regional homogeneity (ReHo), amplitude of low-frequency fluctuation (ALFF), and fractional ALFF (fALFF). Additional functions include DICOM sorting, linear trend removal, bandpass filtering, time course extraction, regression of covariates, image calculation, and statistical analysis. REST is open-source and freely available at http://www.restfmri.net. The paper also provides a detailed description of the algorithms used in REST, including functional connectivity, ReHo, and ALFF, and demonstrates its usage through an example dataset. REST has been used in several recent publications and has been shown to be effective in analyzing RS-fMRI data.