New developments in the program packageATSAS(version 2.4) for the processing and analysis of isotropic small-angle X-ray and neutron scattering data are described. They include (i) multiplatform data manipulation and display tools, (ii) programs for automated data processing and calculation of overall parameters, (iii) improved usage of high- and low-resolution models from other structural methods, (iv) new algorithms to build three-dimensional models from weakly interacting oligomeric systems and complexes, and (v) enhanced tools to analyse data from mixtures and flexible systems. The newATSASrelease includes installers for current major platforms (Windows, Linux and Mac OSX) and provides improved indexed user documentation. The web-related developments, including a user discussion forum and a widened online access to runATSASprograms, are also presented.

DAMMIF, a revised implementation of theab-initioshape-determination programDAMMINfor small-angle scattering data, is presented. The program was fully rewritten, and its algorithm was optimized for speed of execution and modified to avoid limitations due to the finite search volume. Symmetry and anisometry constraints can be imposed on the particle shape, similar toDAMMIN. In equivalent conditions,DAMMIFis 25–40 times faster thanDAMMINon a single CPU. The possibility to utilize multiple CPUs is added toDAMMIF. The application is available in binary form for major platforms.

ATSASis a comprehensive software suite for the analysis of small-angle scattering data from dilute solutions of biological macromolecules or nanoparticles. It contains applications for primary data processing and assessment,ab initiobead modelling, and model validation, as well as methods for the analysis of flexibility and mixtures. In addition, approaches are supported that utilize information from X-ray crystallography, nuclear magnetic resonance spectroscopy or atomistic homology modelling to construct hybrid models based on the scattering data. This article summarizes the progress made during the 2.5–2.8ATSASrelease series and highlights the latest developments. These includeAMBIMETER, an assessment of the reconstruction ambiguity of experimental data;DATCLASS, a multiclass shape classification based on experimental data;SASRES, for estimating the resolution ofab initiomodel reconstructions;CHROMIXS, a convenient interface to analyse in-line size exclusion chromatography data;SHANUM, to evaluate the useful angular range in measured data;SREFLEX, to refine available high-resolution models using normal mode analysis;SUPALMfor a rapid superposition of low- and high-resolution models; andSASPy, theATSASplugin for interactive modelling inPyMOL. All these features and other improvements are included in theATSASrelease 2.8, freely available for academic users from https://www.embl-hamburg.de/biosaxs/software.html.