libopenvlbi is an open source library and application suite for astronomical interferometry.
Interferometry is a discipline that studies the beam or stream interference and the obtainability of a coherence degree between more of them. A 2d interference plot of a single object observed from different locations (space domain Fourier plane dependent to the location of the receivers) shows the power distribution of the radiation pattern or shape of the object observed.
libopenvlbi offers functions to applications that use it to make interferometry simpler and faster.
This website offers an online OpenVLBI JSON service.
The JSON API docs are still being written and will be available soon.
I encourage you to visit the github repository at https://github.com/iliaplatone/OpenVLBI or https://iliaplatone.github.io/OpenVLBI for futher information.