diff --git a/README.md b/README.md
index 6430a19..f9bb042 100644
--- a/README.md
+++ b/README.md
@@ -17,22 +17,23 @@ $ pip3 install elicznik
 
 With the package installed readings can be retrieved by simply running the `elicznik` command:
 ```
-usage: elicznik [-h] [--format {raw,table,csv}] username password [start date] [end date]
+usage: elicznik [-h] [--format {table,csv}] [--api {chart,csv}] username password [start_date] [end_date]
 
 positional arguments:
   username              tauron-dystrybucja.pl user name
   password              tauron-dystrybucja.pl password
-  start date            Start date of date range to be retrieved, in ISO8601 format. If the end date is omitted, it's the only date for which
+  start_date            Start date of date range to be retrieved, in ISO8601 format. If the end date is omitted, it's the only date for which
                         measurements are retrieved.
-  end date              End date of date range to be retrieved, inclusive, in ISO8601 format. Can be omitted to only retrieve a single day's
+  end_date              End date of date range to be retrieved, inclusive, in ISO8601 format. Can be omitted to only retrieve a single day's
                         measurements.
 
-optional arguments:
+options:
   -h, --help            show this help message and exit
-  --format {raw,table,csv}
-                        Specify the output format
+  --format {table,csv}  Specify the output format
+  --api {chart,csv}     Specify which Tauron API to use to get the measurements.
 ```
 
+
 ### Example
 
 ```
@@ -92,6 +93,32 @@ with elicznik.ELicznik("freddy@example.com", "secretpassword") as m:
 ```
 
 
+## Notes on APIs and the `--api` command line switch
+
+Tauron exposes two API endpoints for retrieving meter readings -- one for downloading CSV (and XLS) data,
+the other is a back-end supporting the charts in the Web UI.  In theory, both endpoints are equivalent.
+They can be used to get exactly the same data.  In practice, the endpoint for downloading CSV data seems
+more stable -- in contrast to the chart one, which changed a few times in the past.  The CSV endpoint is
+also more robust and allows downloading more data with fewer requests.
+
+This project supports fetching data from both.  CSV is the default and recommended one, but it's possible
+to switch to the chart API endpoint in case of problems.
+
+This can be done by adding `--api=chart` on the command line:
+```
+$ elicznik --api=chart freddy@example.com secretpassword 2021-07-10
+```
+
+Both APIs can also be used explicitly from code.  The `elicznik` module defines two classes for that `ELicznikChart`
+and `ELicznikCSV`.  `ELicznik` is just an alias for `ELicznikCSV`:
+```
+import elicznik
+
+with elicznik.ELicznikChart("freddy@example.com", "secretpassword") as m:
+    ...
+```
+
+
 ## TODO & bugs
 
 * Add support for accounts with multiple meters
diff --git a/src/elicznik/__init__.py b/src/elicznik/__init__.py
index 55f6f10..3b9ed81 100644
--- a/src/elicznik/__init__.py
+++ b/src/elicznik/__init__.py
@@ -1 +1 @@
-from .elicznik import ELicznik
+from .elicznik import ELicznik, ELicznikChart, ELicznikCSV
diff --git a/src/elicznik/__main__.py b/src/elicznik/__main__.py
index 2c4fd5d..fa504ad 100644
--- a/src/elicznik/__main__.py
+++ b/src/elicznik/__main__.py
@@ -5,7 +5,7 @@ import sys
 
 import tabulate
 
-from .elicznik import ELicznik
+from .elicznik import ELicznikChart, ELicznikCSV
 
 
 def main():
@@ -16,6 +16,12 @@ def main():
         default="table",
         help="Specify the output format",
     )
+    parser.add_argument(
+        "--api",
+        choices=["chart", "csv"],
+        default="csv",
+        help="Specify which Tauron API to use to get the measurements. "
+    )
     parser.add_argument("username", help="tauron-dystrybucja.pl user name")
     parser.add_argument("password", help="tauron-dystrybucja.pl password")
     parser.add_argument(
@@ -39,7 +45,9 @@ def main():
 
     args = parser.parse_args()
 
-    with ELicznik(args.username, args.password) as elicznik:
+    elicznik_class = ELicznikCSV if args.api == "csv" else ELicznikChart
+
+    with elicznik_class(args.username, args.password) as elicznik:
         result = elicznik.get_readings(args.start_date, args.end_date)
 
         if args.format == "table":
diff --git a/src/elicznik/elicznik.py b/src/elicznik/elicznik.py
index e59a199..d548fae 100755
--- a/src/elicznik/elicznik.py
+++ b/src/elicznik/elicznik.py
@@ -5,10 +5,8 @@ import datetime
 
 from .session import Session
 
-
-class ELicznik:
+class ELicznikBase:
     LOGIN_URL = "https://logowanie.tauron-dystrybucja.pl/login"
-    DATA_URL = "https://elicznik.tauron-dystrybucja.pl/energia/do/dane"
 
     def __init__(self, username, password):
         self.username = username
@@ -33,7 +31,48 @@ class ELicznik:
     def __exit__(self, exc_type, exc_val, exc_tb):
         pass
 
-    def get_raw_data(self, start_date, end_date=None):
+
+class ELicznikChart(ELicznikBase):
+    CHART_URL = "https://elicznik.tauron-dystrybucja.pl/energia/api"
+
+    def _get_raw_daily_readings(self, type_, date):
+        data = self.session.post(
+            self.CHART_URL,
+            data={
+                "type": type_,
+                "from": date.strftime("%d.%m.%Y"),
+                "to": date.strftime("%d.%m.%Y"),
+                "profile": "full time",
+            },
+        ).json().get("data", {}).get("values", [])
+
+        return ((datetime.datetime.combine(date, datetime.time(h)), value) for h, value in enumerate(data))
+
+    def _get_raw_readings(self, type_, start_date, end_date=None):
+        end_date = end_date or start_date
+        while start_date <= end_date:
+            yield from self._get_raw_daily_readings(type_, start_date)
+            start_date += datetime.timedelta(days=1)
+
+    def get_readings_production(self, start_date, end_date=None):
+        return dict(self._get_raw_readings("oze", start_date, end_date))
+
+    def get_readings_consumption(self, start_date, end_date=None):
+        return dict(self._get_raw_readings("consum", start_date, end_date))
+
+    def get_readings(self, start_date, end_date=None):
+        consumed = self.get_readings_consumption(start_date, end_date)
+        produced = self.get_readings_production(start_date, end_date)
+        return sorted(
+            (timestamp, consumed.get(timestamp), produced.get(timestamp))
+            for timestamp in set(consumed) | set(produced)
+        )
+
+
+class ELicznikCSV(ELicznikBase):
+    DATA_URL = "https://elicznik.tauron-dystrybucja.pl/energia/do/dane"
+
+    def _get_raw_data(self, start_date, end_date=None):
         end_date = end_date or start_date
         return self.session.post(
             self.DATA_URL,
@@ -48,20 +87,18 @@ class ELicznik:
         ).text.splitlines()
 
     @staticmethod
-    def parse_timestamp(timespec):
+    def _parse_timestamp(timespec):
         date, time = timespec.split(None, 1)
         hour = int(time.split(":")[0]) - 1
-        return datetime.datetime.strptime(date, "%Y-%m-%d") + datetime.timedelta(
-            hours=hour
-        )
+        return datetime.datetime.strptime(date, "%Y-%m-%d") + datetime.timedelta(hours=hour)
 
     def get_readings(self, start_date, end_date=None):
         end_date = end_date or start_date
-        data = self.get_raw_data(start_date, end_date)
+        data = self._get_raw_data(start_date, end_date)
 
         records = [
             {
-                "timestamp": self.parse_timestamp(rec["Data"]),
+                "timestamp": self._parse_timestamp(rec["Data"]),
                 "value": float(rec[" Wartość kWh"].replace(",", ".")),
                 "type": rec["Rodzaj"],
             }
@@ -75,12 +112,14 @@ class ELicznik:
         ]
 
         prod = {
-            rec["timestamp"]: rec["value"] for rec in records if rec["type"] == "pobór"
+            rec["timestamp"]: rec["value"]
+            for rec in records
+            if rec["type"] == "oddanie"
         }
         cons = {
             rec["timestamp"]: rec["value"]
             for rec in records
-            if rec["type"] == "oddanie"
+            if rec["type"] == "pobór"
         }
 
         # TODO
@@ -90,3 +129,5 @@ class ELicznik:
             (timestamp, cons.get(timestamp), prod.get(timestamp))
             for timestamp in set(cons) | set(prod)
         )
+
+ELicznik = ELicznikCSV