Version 3 of the REopt API is currently the stable version of the API.
The inputs and outputs for optimization jobs are revised in v3 for clarity and ease-of-use. Please see our help documentation for creating/converting to V3 inputs .json POST for more information.
The REopt.jl Julia package is used as the optimization engine for the V3 (stable) version of the API. The I/O of the API largely mirrors REopt.jl. You can also access REopt.jl directly in a Julia environment, with documentation about I/O available at REopt Julia package
Information for developers regarding V3 can be found at the REopt API GitHub Wiki page