MobiDB is a database of intrinsically disordered regions (IDRs) and related features from various sources and prediction tools. Different levels of reliability and different features are reported as different and independent annotations. The database features three levels of annotation: manually curated, indirect and predicted. MobiDB annotates the binding modes of disordered proteins, whether they undergo disorder-to-order transitions or remain disordered in the bound state. In addition, disordered regions undergoing liquid-liquid phase separation or post-translational modifications are defined.