The Reactome pathway Knowledgebase provides molecular details of cellular processes such as signal transduction, transport, DNA replication, and metabolism as an ordered network of molecular transformations. It functions as both an archive of biological processes and a tool for discovering unexpected functional relationships in data such as gene expression patterns or somatic mutation catalogues. Over the past two years, major components of the Reactome web interface have been redeveloped to improve usability, responsiveness, and data visualization. A new pathway diagram viewer provides a faster, clearer interface and smooth zooming from the entire reaction network to individual reactions. Tool performance for analysis of user datasets has been substantially improved, now generating detailed results for genome-wide expression datasets within seconds. The analysis module can now be accessed through a RESTful interface, facilitating its inclusion in third-party applications. A new overview module allows the visualization of analysis results on a genome-wide Reactome pathway hierarchy using a single screen page. The search interface now provides auto-completion as well as a faceted search to narrow result lists efficiently. Reactome pathways are organized hierarchically, grouping detailed pathways into larger domains of biological function. The pathway overview visualization provides an overview of all Reactome pathways, highlighting parent-child relationships and shared processes. The pathway browser has been updated to reduce loading time and provide a more attractive user interface. The pathway analysis tool allows users to overlay experimental datasets on annotations to search for patterns in the dataset such as modulation of specific pathways. A new RESTful web service interface supports high-throughput pathway analysis and allows batch dataset analysis. The search tool has been redesigned to provide fast data access and incorporate additional data type attributes, yielding more accurate search results. The changes to the Reactome site and data analysis tools described here provide users with faster, easier access to Reactome data, increasing its utility both as an archive of known human biology and as a tool for generating and testing experimental hypotheses.The Reactome pathway Knowledgebase provides molecular details of cellular processes such as signal transduction, transport, DNA replication, and metabolism as an ordered network of molecular transformations. It functions as both an archive of biological processes and a tool for discovering unexpected functional relationships in data such as gene expression patterns or somatic mutation catalogues. Over the past two years, major components of the Reactome web interface have been redeveloped to improve usability, responsiveness, and data visualization. A new pathway diagram viewer provides a faster, clearer interface and smooth zooming from the entire reaction network to individual reactions. Tool performance for analysis of user datasets has been substantially improved, now generating detailed results for genome-wide expression datasets within seconds. The analysis module can now be accessed through a RESTful interface, facilitating its inclusion in third-party applications. A new overview module allows the visualization of analysis results on a genome-wide Reactome pathway hierarchy using a single screen page. The search interface now provides auto-completion as well as a faceted search to narrow result lists efficiently. Reactome pathways are organized hierarchically, grouping detailed pathways into larger domains of biological function. The pathway overview visualization provides an overview of all Reactome pathways, highlighting parent-child relationships and shared processes. The pathway browser has been updated to reduce loading time and provide a more attractive user interface. The pathway analysis tool allows users to overlay experimental datasets on annotations to search for patterns in the dataset such as modulation of specific pathways. A new RESTful web service interface supports high-throughput pathway analysis and allows batch dataset analysis. The search tool has been redesigned to provide fast data access and incorporate additional data type attributes, yielding more accurate search results. The changes to the Reactome site and data analysis tools described here provide users with faster, easier access to Reactome data, increasing its utility both as an archive of known human biology and as a tool for generating and testing experimental hypotheses.