diff --git a/catalog_tools/io/client.py b/catalog_tools/io/client.py
new file mode 100644
index 0000000..f2554ec
--- /dev/null
+++ b/catalog_tools/io/client.py
@@ -0,0 +1,98 @@
+from datetime import datetime
+from typing import Optional
+from xml.sax import handler, make_parser
+
+import pandas as pd
+import requests
+
+from catalog_tools.download.download_qml import CustomContentHandler
+
+
+class FDSNWSEventClient():
+    def __init__(self, url: str):
+        """
+        Args:
+            url:    base url of the FDSNWS event service 
+                    (eg. 'https://earthquake.usgs.gov/fdsnws/event/1/query')
+        """
+
+        self.url = url
+
+    def get_events(self, start_time: Optional[datetime] = None,
+                   end_time: Optional[datetime] = None,
+                   min_latitude: Optional[float] = None,
+                   max_latitude: Optional[float] = None,
+                   min_longitude: Optional[float] = None,
+                   max_longitude: Optional[float] = None,
+                   min_magnitude: Optional[float] = None,
+                   include_all_magnitudes: Optional[bool] = None,
+                   event_type: Optional[str] = None,
+                   delta_m: float = 0.1) -> pd.DataFrame:
+        """Downloads an earthquake catalog based on a URL.
+
+        Args:
+            base_query:     base query url ()
+            start_time:     start time of the catalog.
+            end_time:       end time of the catalog. defaults to current time.
+            min_latitude:   minimum latitude of catalog.
+            max_latitude:   maximum latitude of catalog.
+            min_longitude:  minimum longitude of catalog.
+            max_longitude:  maximum longitude of catalog.
+            min_magnitude:  minimum magnitude of catalog.
+            include_all_magnitudes: whether to include all magnitudes.
+            event_type:     type of event to download.
+            delta_m:        magnitude bin size. if >0, then events of
+                magnitude >= (min_magnitude - delta_m/2) will be downloaded.
+
+        Returns:
+            The catalog as a pandas DataFrame.
+
+        """
+        request_url = self.url + '?'
+        date_format = "%Y-%m-%dT%H:%M:%S"
+
+        if start_time:
+            request_url += f'&starttime={start_time.strftime(date_format)}'
+        if end_time:
+            request_url += f'&endtime={end_time.strftime(date_format)}'
+        if min_latitude:
+            request_url += f'&minlatitude={min_latitude}'
+        if max_latitude:
+            request_url += f'&maxlatitude={max_latitude}'
+        if min_longitude:
+            request_url += f'&minlongitude={min_longitude}'
+        if max_longitude:
+            request_url += f'&maxlongitude={max_longitude}'
+        if min_magnitude and delta_m:
+            request_url += f'&minmagnitude={min_magnitude - (delta_m / 2)}'
+        elif min_magnitude:
+            request_url += f'&minmagnitude={min_magnitude}'
+        if include_all_magnitudes:
+            request_url += f'&includeallmagnitudes={include_all_magnitudes}'
+
+        print(request_url)
+
+        catalog = []
+        parser = make_parser()
+        parser.setFeature(handler.feature_namespaces, False)
+        parser.setContentHandler(CustomContentHandler(catalog))
+
+        r = requests.get(request_url, stream=True)
+        r.raw.decode_content = True  # if content-encoding is used decode
+        parser.parse(r.raw)
+        df = pd.DataFrame.from_dict(catalog)
+        return df
+
+
+def main():
+    url = 'https://earthquake.usgs.gov/fdsnws/event/1/query'
+    url2 = 'http://arclink.ethz.ch/fdsnws/event/1/query'
+    client = FDSNWSEventClient(url2)
+    cat = client.get_events(start_time=datetime(
+        2023, 7, 1))
+    print(cat[cat['magnitude_value'].isna()])
+    print(cat.columns)
+
+
+if __name__ == '__main__':
+    main()