Inventory API get and add (post) contact in nodejs, javscript

I am trying to push existing data to Zoho via API calls and that is not working.

https://inventory.zoho.com/api/v1/items?authtoken=****&organization_id=***** returns

{"code":6,"message":"Internal Error"}

To insert, I am doing the following

  const 
  params = {
  
  authtoken: 
  '******',
  
  organization_id: 
  *****,
  
  JSONString: 
  JSON.
  stringify({ 
  contact_name: 
  'Bowman and Co' }),
  
  };
 
  HTTP.
  post(
  'https://inventory.zoho.com/api/v1/contacts',
  
  {
  
  params,
  
  },
  
  (
  err, 
  response) 
  => {
  
  if (
  err) {
  
  return 
  console.
  error(
  'upload failed:', 
  err);
  
  }
  
  console.
  log(
  'Upload successful! Server responded with:', 
  response);
  
  return 
  response;
  
  })

response: { statusCode: 400,content: '{"code":2,"message":"The request passed is not valid."}',

Will someone be able to help? Without this I will not be able to start.