Obba provides a bridge between spreadsheets and Java classes. With Obba, you can use spreadsheets as GUIs (Graphical User Interfaces) for your Java libraries. Loading of arbitrary jar or class files at runtime through a spreadsheet function. Instantiation of Java objects, storing the object reference under a given object label. Invocation of methods on objects referenced by their object handle, storing the handle to the result under a given object label. Asynchronous method invocation and tools for synchronization, turning your spreadsheet into a multi-threaded calculation tool. Allows arbitrary number of arguments for constructors or methods (avoids the limitation of the number of arguments for Excel worksheet functions). Serialization and de-serialization (save serializable objects to a file, restore them any time later). All this though spreadsheet functions, without any additional line of code (no VBA needed, no additional Java code needed). For a tutorial see Obba tutorial. In this tutorial you create a Java class and a spreadsheet to fetch Stock quotes from yahoo finance. For a more detailed introduction see documentation.