MOTIVATION: Mass spectrometry-based phosphoproteomics can routinely identify and quantify thousands of phosphorylated peptides from a single experiment. However interrogating possible upstream kinases and identifying key literature for phosphorylation sites is laborious and time-consuming. RESULTS: Here, we present Phosphomatics-a publicly available web resource for interrogating phosphoproteomics data. Phosphomatics allows researchers to upload phosphoproteomics data and interrogate possible relationships from a substrate-, kinase- or pathway-centric viewpoint. AVAILABILITY AND IMPLEMENTATION: Phosphomatics is freely available via the internet at: https://phosphomatics.com. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.