[malbs]

For Delphi it is a combo of the Indy project (IdHttp), and superobject (probably other json parsers too but superobject is quick and fairly solid).

However, given I've yet to find Delphi code that straight up compiles in Lazarus/FreePascal, you probably have your work cut out for you, but if you google for [superobject/indy] for Lazarus, others have started those hikes, and you may find there are working versions of one, or possibly both of them. I've never looked.