diff --git a/chat_archiver/chat_archiver/main.py b/chat_archiver/chat_archiver/main.py
index 4a808ac..4844086 100644
--- a/chat_archiver/chat_archiver/main.py
+++ b/chat_archiver/chat_archiver/main.py
@@ -1,6 +1,5 @@
 
 import base64
-import errno
 import hashlib
 import json
 import logging
@@ -19,15 +18,13 @@ from uuid import uuid4
 import gevent.event
 import gevent.queue
 
-from common import ensure_directory
-from common.stats import timed
+from common import ensure_directory, listdir
+from common.chat import BATCH_INTERVAL, format_batch, get_batch_files, merge_messages
 
 from girc import Client
 from monotonic import monotonic
 import prometheus_client as prom
 
-# How long each batch is
-BATCH_INTERVAL = 60
 
 # These are known to arrive up to MAX_DELAY after their actual time
 DELAYED_COMMANDS = [
@@ -271,16 +268,6 @@ class Archiver(object):
 		self.client.stop()
 
 
-def listdir(path):
-	"""as os.listdir but return [] if dir doesn't exist"""
-	try:
-		return os.listdir(path)
-	except OSError as e:
-		if e.errno != errno.ENOENT:
-			raise
-		return []
-
-
 def write_batch(path, batch_time, messages, size_histogram=None):
 	"""Batches are named PATH/YYYY-MM-DDTHH/MM:SS-HASH.json"""
 	output = (format_batch(messages) + '\n').encode('utf-8')
@@ -303,32 +290,6 @@ def write_batch(path, batch_time, messages, size_histogram=None):
 	return filepath
 
 
-def format_batch(messages):
-	# We need to take some care to have a consistent ordering and format here.
-	# We use a "canonicalised JSON" format, which is really just whatever the python encoder does,
-	# with compact separators and sorted keys.
-	messages = [
-		(message, json.dumps(message, separators=(',', ':'), sort_keys=True))
-		for message in messages
-	]
-	# We sort by timestamp, then timestamp range, then if all else fails, lexiographically
-	# on the encoded representation.
-	messages.sort(key=lambda item: (item[0]['time'], item[0]['time_range'], item[1]))
-	return "\n".join(line for message, line in messages)
-
-
-def get_batch_files(path, batch_time):
-	"""Returns list of batch filepaths for a given batch time"""
-	hour = datetime.utcfromtimestamp(batch_time).strftime("%Y-%m-%dT%H")
-	time = datetime.utcfromtimestamp(batch_time).strftime("%M:%S")
-	hourdir = os.path.join(path, hour)
-	return [
-		os.path.join(hourdir, name)
-		for name in listdir(hourdir)
-		if name.startswith(time) and name.endswith(".json")
-	]
-
-
 def merge_all(path, interval=None, stopping=None):
 	"""Repeatedly scans the batch directory for batch files with the same batch time, and merges them.
 	By default, returns once it finds no duplicate files.
@@ -418,100 +379,6 @@ def merge_batch_files(path, batch_time):
 		if batch_file not in written:
 			os.remove(batch_file)
 
-@timed("merge_messages", normalize=lambda _, left, right: len(left) + len(right))
-def merge_messages(left, right):
-	"""Merges two lists of messages into one merged list.
-	This operation should be a CRDT, ie. all the following hold:
-	- associative: merge(merge(A, B), C) == merge(A, merge(B, C))
-	- commutitive: merge(A, B) == merge(B, A)
-	- reflexive: merge(A, A) == A
-	This means that no matter what order information from different sources
-	is incorporated (or if sources are repeated), the results should be the same.
-	"""
-	# An optimization - if either size is empty, return the other side without processing.
-	if not left:
-		return right
-	if not right:
-		return left
-
-	# Calculates intersection of time range of both messages, or None if they don't overlap
-	def overlap(a, b):
-		range_start = max(a['time'], b['time'])
-		range_end = min(a['time'] + a['time_range'], b['time'] + b['time_range'])
-		if range_end < range_start:
-			return None
-		return range_start, range_end - range_start
-		
-	# Returns merged message if two messages are compatible with being the same message,
-	# or else None.
-	def merge_message(a, b):
-		o = overlap(a, b)
-		if o and all(
-			a.get(k) == b.get(k)
-			for k in set(a.keys()) | set(b.keys())
-			if k not in ("receivers", "time", "time_range")
-		):
-			receivers = a["receivers"] | b["receivers"]
-			# Error checking - make sure no receiver timestamps are being overwritten.
-			# This would indicate we're merging two messages recieved at different times
-			# by the same recipient.
-			for k in receivers.keys():
-				for old in (a, b):
-					if k in old and old[k] != receivers[k]:
-						raise ValueError(f"Merge would merge two messages with different recipient timestamps: {a}, {b}")
-			return a | {
-				"time": o[0],
-				"time_range": o[1],
-				"receivers": receivers,
-			}
-		return None
-
-	# Match things with identical ids first, and collect unmatched into left and right lists
-	by_id = {}
-	unmatched = [], []
-	for messages, u in zip((left, right), unmatched):
-		for message in messages:
-			id = (message.get('tags') or {}).get('id')
-			if id:
-				by_id.setdefault(id, []).append(message)
-			else:
-				u.append(message)
-
-	result = []
-	for id, messages in by_id.items():
-		if len(messages) == 1:
-			logging.debug(f"Message with id {id} has no match")
-			result.append(messages[0])
-		else:
-			merged = merge_message(*messages)
-			if merged is None:
-				raise ValueError(f"Got two non-matching messages with id {id}: {messages[0]}, {messages[1]}")
-			logging.debug(f"Merged messages with id {id}")
-			result.append(merged)
-
-	# For time-range messages, pair off each one in left with first match in right,
-	# and pass through anything with no matches.
-	left_unmatched, right_unmatched = unmatched
-	for message in left_unmatched:
-		for other in right_unmatched:
-			merged = merge_message(message, other)
-			if merged:
-				logging.debug(
-					"Matched {m[command]} message {a[time]}+{a[time_range]} & {b[time]}+{b[time_range]} -> {m[time]}+{m[time_range]}"
-					.format(a=message, b=other, m=merged)
-				)
-				right_unmatched.remove(other)
-				result.append(merged)
-				break
-		else:
-			logging.debug("No match found for {m[command]} at {m[time]}+{m[time_range]}".format(m=message))
-			result.append(message)
-	for message in right_unmatched:
-		logging.debug("No match found for {m[command]} at {m[time]}+{m[time_range]}".format(m=message))
-		result.append(message)
-
-	return result
-
 
 def main(channel, nick, oauth_token_path, base_dir='/mnt', name=None, merge_interval=60):
 	with open(oauth_token_path) as f:
diff --git a/chat_archiver/chat_archiver/merge.py b/chat_archiver/chat_archiver/merge.py
index 50a2abc..ad60710 100644
--- a/chat_archiver/chat_archiver/merge.py
+++ b/chat_archiver/chat_archiver/merge.py
@@ -3,7 +3,7 @@ import argh
 import logging
 import json
 
-from .main import merge_messages, format_batch
+from common.chat import merge_messages, format_batch
 
 def main(*paths, log='INFO'):
 	"""Merge all listed batch files and output result to stdout"""
diff --git a/chat_archiver/chat_archiver/merge_all.py b/chat_archiver/chat_archiver/merge_all.py
index a9f0e65..166b56c 100644
--- a/chat_archiver/chat_archiver/merge_all.py
+++ b/chat_archiver/chat_archiver/merge_all.py
@@ -1,9 +1,8 @@
 
 import argh
 import logging
-import json
 
-from .main import merge_messages, format_batch, merge_all
+from .main import merge_all
 
 def main(path, log='INFO'):
 	"""Merge all batch files with the same timestamp within given directory"""
diff --git a/common/common/__init__.py b/common/common/__init__.py
index f906d54..8f288c2 100644
--- a/common/common/__init__.py
+++ b/common/common/__init__.py
@@ -150,3 +150,13 @@ def serve_with_graceful_shutdown(server, stop_timeout=20):
 	logging.info("Shutting down")
 	server.stop(stop_timeout)
 	logging.info("Gracefully shut down")
+
+
+def listdir(path):
+	"""as os.listdir but return [] if dir doesn't exist"""
+	try:
+		return os.listdir(path)
+	except OSError as e:
+		if e.errno != errno.ENOENT:
+			raise
+		return []
diff --git a/common/common/chat.py b/common/common/chat.py
new file mode 100644
index 0000000..42c3cdb
--- /dev/null
+++ b/common/common/chat.py
@@ -0,0 +1,152 @@
+
+import json
+import logging
+import os
+from datetime import datetime, timedelta
+
+from common import listdir
+from common.stats import timed
+from common.segments import hour_paths_for_range
+
+
+# How long each batch is
+BATCH_INTERVAL = 60
+
+
+def format_batch(messages):
+	# We need to take some care to have a consistent ordering and format here.
+	# We use a "canonicalised JSON" format, which is really just whatever the python encoder does,
+	# with compact separators and sorted keys.
+	messages = [
+		(message, json.dumps(message, separators=(',', ':'), sort_keys=True))
+		for message in messages
+	]
+	# We sort by timestamp, then timestamp range, then if all else fails, lexiographically
+	# on the encoded representation.
+	messages.sort(key=lambda item: (item[0]['time'], item[0]['time_range'], item[1]))
+	return "\n".join(line for message, line in messages)
+
+
+def get_batch_files(path, batch_time):
+	"""Returns list of batch filepaths for a given batch time as unix timestamp"""
+	hour = datetime.utcfromtimestamp(batch_time).strftime("%Y-%m-%dT%H")
+	time = datetime.utcfromtimestamp(batch_time).strftime("%M:%S")
+	hourdir = os.path.join(path, hour)
+	return [
+		os.path.join(hourdir, name)
+		for name in listdir(hourdir)
+		if name.startswith(time) and name.endswith(".json")
+	]
+
+
+def get_batch_file_range(hours_path, start, end):
+	"""Returns list of batch filepaths covering at least the time range given, but possibly longer.
+	May contain multiple results with the same timestamp.
+	start and end must be datetimes.
+	"""
+	# pad start and end to capture neighboring batches, including messages
+	# with a wide time range, which might actually be in an even earlier batch.
+	start -= timedelta(seconds=2 * BATCH_INTERVAL)
+	end += timedelta(seconds=BATCH_INTERVAL)
+	for hour_path in hour_paths_for_range(hours_path, start, end):
+		hour = os.path.basename(hour_path)
+		for name in listdir(hour_path):
+			min_sec = name.split("-")[0]
+			timestamp = datetime.strptime("{}:{}".format(hour, min_sec), "%Y-%m-%dT%H:%M:%S")
+			if start < timestamp < end:
+				yield os.path.join(hour_path, name)
+
+
+@timed("merge_messages", normalize=lambda _, left, right: len(left) + len(right))
+def merge_messages(left, right):
+	"""Merges two lists of messages into one merged list.
+	This operation should be a CRDT, ie. all the following hold:
+	- associative: merge(merge(A, B), C) == merge(A, merge(B, C))
+	- commutitive: merge(A, B) == merge(B, A)
+	- reflexive: merge(A, A) == A
+	This means that no matter what order information from different sources
+	is incorporated (or if sources are repeated), the results should be the same.
+	"""
+	# An optimization - if either size is empty, return the other side without processing.
+	if not left:
+		return right
+	if not right:
+		return left
+
+	# Calculates intersection of time range of both messages, or None if they don't overlap
+	def overlap(a, b):
+		range_start = max(a['time'], b['time'])
+		range_end = min(a['time'] + a['time_range'], b['time'] + b['time_range'])
+		if range_end < range_start:
+			return None
+		return range_start, range_end - range_start
+
+	# Returns merged message if two messages are compatible with being the same message,
+	# or else None.
+	def merge_message(a, b):
+		o = overlap(a, b)
+		if o and all(
+			a.get(k) == b.get(k)
+			for k in set(a.keys()) | set(b.keys())
+			if k not in ("receivers", "time", "time_range")
+		):
+			receivers = a["receivers"] | b["receivers"]
+			# Error checking - make sure no receiver timestamps are being overwritten.
+			# This would indicate we're merging two messages recieved at different times
+			# by the same recipient.
+			for k in receivers.keys():
+				for old in (a, b):
+					if k in old and old[k] != receivers[k]:
+						raise ValueError(f"Merge would merge two messages with different recipient timestamps: {a}, {b}")
+			return a | {
+				"time": o[0],
+				"time_range": o[1],
+				"receivers": receivers,
+			}
+		return None
+
+	# Match things with identical ids first, and collect unmatched into left and right lists
+	by_id = {}
+	unmatched = [], []
+	for messages, u in zip((left, right), unmatched):
+		for message in messages:
+			id = (message.get('tags') or {}).get('id')
+			if id:
+				by_id.setdefault(id, []).append(message)
+			else:
+				u.append(message)
+
+	result = []
+	for id, messages in by_id.items():
+		if len(messages) == 1:
+			logging.debug(f"Message with id {id} has no match")
+			result.append(messages[0])
+		else:
+			merged = merge_message(*messages)
+			if merged is None:
+				raise ValueError(f"Got two non-matching messages with id {id}: {messages[0]}, {messages[1]}")
+			logging.debug(f"Merged messages with id {id}")
+			result.append(merged)
+
+	# For time-range messages, pair off each one in left with first match in right,
+	# and pass through anything with no matches.
+	left_unmatched, right_unmatched = unmatched
+	for message in left_unmatched:
+		for other in right_unmatched:
+			merged = merge_message(message, other)
+			if merged:
+				logging.debug(
+					"Matched {m[command]} message {a[time]}+{a[time_range]} & {b[time]}+{b[time_range]} -> {m[time]}+{m[time_range]}"
+					.format(a=message, b=other, m=merged)
+				)
+				right_unmatched.remove(other)
+				result.append(merged)
+				break
+		else:
+			logging.debug("No match found for {m[command]} at {m[time]}+{m[time_range]}".format(m=message))
+			result.append(message)
+	for message in right_unmatched:
+		logging.debug("No match found for {m[command]} at {m[time]}+{m[time_range]}".format(m=message))
+		result.append(message)
+
+	return result
diff --git a/restreamer/restreamer/main.py b/restreamer/restreamer/main.py
index ee45ea5..c64cc50 100644
--- a/restreamer/restreamer/main.py
+++ b/restreamer/restreamer/main.py
@@ -17,6 +17,7 @@ from gevent.pywsgi import WSGIServer
 from common import dateutil, get_best_segments, rough_cut_segments, fast_cut_segments, full_cut_segments, PromLogCountsHandler, install_stacksampler, serve_with_graceful_shutdown
 from common.flask_stats import request_stats, after_request
 from common.segments import feed_input, render_segments_waveform, extract_frame, list_segment_files
+from common.chat import get_batch_file_range, merge_messages
 
 from . import generate_hls
 
@@ -91,8 +92,8 @@ def metrics():
 @app.route('/metrics/<trailing>')
 @request_stats
 def metrics_with_trailing(trailing):
-       """Expose Prometheus metrics."""
-       return prom.generate_latest()
+	"""Expose Prometheus metrics."""
+	return prom.generate_latest()
 
 @app.route('/files')
 @request_stats
@@ -393,6 +394,60 @@ def get_frame(channel, quality):
 	return Response(extract_frame(segments, timestamp), mimetype='image/png')
 
 
+@app.route('/<channel>/chat.json')
+@request_stats
+@has_path_args
+def get_chat_messages(channel):
+	"""
+	Returns a JSON list of chat messages from the given time range.
+	The messages are in the same format as used in the chat archiver.
+	Messages without an exact known time are included if their possible time range
+	intersects with the requested time range. Note this means that messages in range (A, B)
+	and range (B, C) may overlap! Thankfully the kinds of messages this can happen for mostly
+	don't matter - JOINs and PARTs mainly, but sometimes ROOMSTATEs, NOTICEs and CLEARCHATs.
+	Params:
+		start, end: Required. The start and end times.
+			Must be in ISO 8601 format (ie. yyyy-mm-ddTHH:MM:SS) and UTC.
+	"""
+	start = dateutil.parse_utc_only(request.args['start'])
+	end = dateutil.parse_utc_only(request.args['end'])
+	if end <= start:
+		return "End must be after start", 400
+
+	hours_path = os.path.join(app.static_folder, channel, "chat")
+
+	# This process below may fail if a batch is deleted out from underneath us.
+	# If that happens, we need to start again.
+	retry = True
+	while retry:
+		retry = False
+		messages = []
+		for batch_file in get_batch_file_range(hours_path, start, end):
+			try:
+				with open(batch_file) as f:
+					batch = f.read()
+			except OSError as e:
+				if e.errno != errno.ENOENT:
+					raise
+				# If file doesn't exist, retry the outer loop
+				retry = True
+				break
+			batch = [json.loads(line) for line in batch.strip().split("\n")]
+			messages = merge_messages(messages, batch)
+
+	start = start.timestamp()
+	end = end.timestamp()
+	messages = sorted(
+		[
+			m for m in messages
+			# message ends after START, and starts before END
+			if start <= m['time'] + m['time_range'] and m['time'] < end
+		], key=lambda m: (m['time'], m['time_range'])
+	)
+
+	return json.dumps(messages)
+
+
 @app.route('/generate_videos/<channel>/<quality>', methods=['POST'])
 @request_stats
 @has_path_args