The Sumset Generator, written by Professor Ivaylo Ilinkin, generates sumsets with specified parameters. Other project contributors include Samir Lalvani (initial prototype), John Llano (advanced settings).
AddComb.js is a javascript library for additive combinatorics computation. At the link above you will find an online interface with various tools, including a function calculator for the functions listed in Professor Béla Bajnok's book on Additive Combinatorics. Also provided is a sumset calculator, table generator, and Jupyter Notebook-style playground for direct interaction with library functions. This code is open source on GitHub.