Fortunately, Google always implements things in language independent way, despite providing easy to use wrappers for certain languages.
Rest API is the way to go. Follow all steps in that link then you can turn the cURL commands into the equivalent for fphttpclient or whatever HTTP client library of your choice. After all, that's what the wrappers do.
For instance, the example:
curl -X PUT -d '{
"alanisawesome": {
"name": "Alan Turing",
"birthday": "June 23, 1912"
}
}' 'https://docs-examples.firebaseio.com/fireblog/users.json'
is equivalent to:
uses
fphttpclient,fpjson;
...
var
obj: TJSONObject;
...
with TFPHTTPClient.Create(nil) do
try
obj := TJSONObject.Create;
obj.Strings['author'] := 'alanisawesome';
obj.Strings['title'] := 'The Turing Machine';
RequestBody := TRawByteStringStream.Create(obj.AsJSON);
obj.Free;
WriteLn(Put('https://docs-examples.firebaseio.com/fireblog/users.json'));
finally
Free;
end;