diff --git a/CHANGES.rst b/CHANGES.rst
index d7866ad8..065f349b 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -6,6 +6,8 @@ Changelog
 incomplete
 ==========
 - Add possibility to acquire bulk readings in JSON format
+- Add possibility to acquire bulk readings in compact JSON format,
+  with timestamps as keys
 
 
 in progress
@@ -94,7 +96,6 @@ Infrastructure
 - QA: Improve tests on HTTP API for data acquisition
 - CI: Add testing against Python 3.9
 - CI: Run tests against different versions of Mosquitto, InfluxDB and Grafana
-- Add possibility to acquire bulk readings in JSON format
 
 
 .. _kotori-0.26.8:
diff --git a/kotori/daq/decoder/__init__.py b/kotori/daq/decoder/__init__.py
index 35b0e3fe..f9a8a874 100644
--- a/kotori/daq/decoder/__init__.py
+++ b/kotori/daq/decoder/__init__.py
@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 # (c) 2019-2021 Andreas Motl <andreas@getkotori.org>
 from kotori.daq.decoder.airrohr import AirrohrDecoder
+from kotori.daq.decoder.json import CompactTimestampedJsonDecoder
 from kotori.daq.decoder.tasmota import TasmotaSensorDecoder, TasmotaStateDecoder
 from kotori.daq.decoder.schema import MessageType
 
@@ -23,6 +24,12 @@ def probe(self):
         if 'slot' not in self.topology:
             return False
 
+        # Compact JSON format, with timestamps as keys
+        if self.topology.slot.endswith('tc.json'):
+            self.info.message_type = MessageType.DATA_CONTAINER
+            self.info.decoder = CompactTimestampedJsonDecoder
+            return True
+
         # Airrohr
         if self.topology.slot.endswith('airrohr.json'):
             self.info.message_type = MessageType.DATA_CONTAINER
diff --git a/kotori/daq/decoder/json.py b/kotori/daq/decoder/json.py
new file mode 100644
index 00000000..5e66de69
--- /dev/null
+++ b/kotori/daq/decoder/json.py
@@ -0,0 +1,44 @@
+# -*- coding: utf-8 -*-
+# (c) 2021 Andreas Motl <andreas@getkotori.org>
+import json
+
+
+class CompactTimestampedJsonDecoder:
+    """
+    Decode JSON payloads in compact format, with timestamps as keys.
+
+    Documentation
+    =============
+    - https://getkotori.org/docs/handbook/decoders/json.html (not yet)
+    - https://github.com/daq-tools/kotori/issues/39
+
+    Example
+    =======
+    ::
+
+        {
+          "1611082554": {
+            "temperature": 21.42,
+            "humidity": 41.55
+          },
+          "1611082568": {
+            "temperature": 42.84,
+            "humidity": 83.1
+          }
+        }
+
+    """
+
+    @staticmethod
+    def decode(payload):
+
+        # Decode from JSON.
+        message = json.loads(payload)
+
+        # Create list of data dictionaries.
+        data = []
+        for timestamp, item in message.items():
+            item["time"] = timestamp
+            data.append(item)
+
+        return data
diff --git a/test/settings/mqttkit.py b/test/settings/mqttkit.py
index 70c328d5..e7e4b910 100644
--- a/test/settings/mqttkit.py
+++ b/test/settings/mqttkit.py
@@ -27,6 +27,7 @@ class TestSettings:
     mqtt_topic3_json   = 'mqttkit-1/itest3/foo/bar/data.json'
     mqtt_topic_event  = 'mqttkit-1/itest/foo/bar/event.json'
     mqtt_topic_homie  = 'mqttkit-1/itest/foo/bar/data/__json__'
+    mqtt_topic_json_compact = 'mqttkit-1/itest/foo/bar/tc.json'
     mqtt_topic_json_legacy = 'mqttkit-1/itest/foo/bar/message-json'
 
     # HTTP channel settings.
diff --git a/test/test_daq_mqtt.py b/test/test_daq_mqtt.py
index 3ca23683..eb0cb857 100644
--- a/test/test_daq_mqtt.py
+++ b/test/test_daq_mqtt.py
@@ -71,6 +71,40 @@ def test_mqtt_to_influxdb_json_bulk(machinery, create_influxdb, reset_influxdb):
     assert record == {u'temperature': 42.84, u'humidity': 83.1}
 
 
+@pytest_twisted.inlineCallbacks
+@pytest.mark.mqtt
+def test_mqtt_to_influxdb_json_compact_bulk(machinery, create_influxdb, reset_influxdb):
+    """
+    Publish multiple readings in compact JSON format to MQTT broker
+    and proof they are stored in the InfluxDB database.
+
+    https://github.com/daq-tools/kotori/issues/39
+    """
+
+    # Submit multiple measurements, with timestamp.
+    data = {
+        "1611082554": {
+            "temperature": 21.42,
+            "humidity": 41.55,
+        },
+        "1611082568": {
+            "temperature": 42.84,
+            "humidity": 83.1,
+        },
+    }
+    yield threads.deferToThread(mqtt_json_sensor, settings.mqtt_topic_json_compact, data)
+
+    # Wait for some time to process the message.
+    yield sleep(PROCESS_DELAY_MQTT)
+
+    # Proof that data arrived in InfluxDB.
+    record = influx_sensors.get_record(index=0)
+    assert record == {u'time': '2021-01-19T18:55:54Z', u'temperature': 21.42, u'humidity': 41.55}
+
+    record = influx_sensors.get_record(index=1)
+    assert record == {u'time': '2021-01-19T18:56:08Z', u'temperature': 42.84, u'humidity': 83.1}
+
+
 @pytest_twisted.inlineCallbacks
 @pytest.mark.mqtt
 @pytest.mark.legacy