How make a http post using form data in flutter?
Use Map instead, because body in http package only has 3 types: String, List<int> or Map<String, String>. Try this: final Uri uri = Uri.parse(‘https://na57.salesforce.com/services/oauth2/token’); final map = <String, dynamic>{}; map[‘grant_type’] = ‘password’; map[‘client_id’] = ‘3MVG9dZJodJWITSviqdj3EnW.LrZ81MbuGBqgIxxxdD6u7Mru2NOEs8bHFoFyNw_nVKPhlF2EzDbNYI0rphQL’; map[‘client_secret’] = ’42E131F37E4E05313646E1ED1D3788D76192EBECA7486D15BDDB8408B9726B42′; map[‘username’] = ‘[email protected]’; map[‘password’] = ‘ABC1234563Af88jesKxPLVirJRW8wXvj3D’; http.Response response = await http.post( uri, body: map, );