diff --git a/fdroidserver/verify.py b/fdroidserver/verify.py
index 053a730b..8025b054 100644
--- a/fdroidserver/verify.py
+++ b/fdroidserver/verify.py
@@ -19,19 +19,108 @@
 import sys
 import os
 import glob
+import json
+import logging
 import requests
 from argparse import ArgumentParser
-import logging
+from collections import OrderedDict
 
 from . import _
 from . import common
 from . import net
+from . import update
 from .exception import FDroidException
 
 options = None
 config = None
 
 
+class hashabledict(OrderedDict):
+    def __key(self):
+        return tuple((k, self[k]) for k in sorted(self))
+
+    def __hash__(self):
+        return hash(self.__key())
+
+    def __eq__(self, other):
+        return self.__key() == other.__key()
+
+    def __lt__(self, other):
+        return self.__key() < other.__key()
+
+    def __qt__(self, other):
+        return self.__key() > other.__key()
+
+
+class Decoder(json.JSONDecoder):
+    def __init__(self, **kwargs):
+        json.JSONDecoder.__init__(self, **kwargs)
+        self.parse_array = self.JSONArray
+        # Use the python implemenation of the scanner
+        self.scan_once = json.scanner.py_make_scanner(self)
+
+    def JSONArray(self, s_and_end, scan_once, **kwargs):
+        values, end = json.decoder.JSONArray(s_and_end, scan_once, **kwargs)
+        return set(values), end
+
+
+class Encoder(json.JSONEncoder):
+    def default(self, obj):
+        if isinstance(obj, set):
+            return sorted(obj)
+        return super().default(obj)
+
+
+def write_json_report(url, remote_apk, unsigned_apk, compare_result):
+    """write out the results of the verify run to JSON
+
+    This builds up reports on the repeated runs of `fdroid verify` on
+    a set of apps.  It uses the timestamps on the compared files to
+    ensure that there is only one report per file, even when run
+    repeatedly.
+
+    """
+
+    jsonfile = unsigned_apk + '.json'
+    if os.path.exists(jsonfile):
+        with open(jsonfile) as fp:
+            data = json.load(fp, object_pairs_hook=OrderedDict)
+    else:
+        data = OrderedDict()
+    output = hashabledict()
+    output['url'] = url
+    for key, filename in (('local', unsigned_apk), ('remote', remote_apk)):
+        d = hashabledict()
+        output[key] = d
+        d['file'] = filename
+        d['sha256'] = update.sha256sum(filename)
+        d['timestamp'] = os.stat(filename).st_ctime
+        d['packageName'], d['versionCode'], d['versionName'] = common.get_apk_id(filename)
+    if compare_result:
+        output['verified'] = False
+        output['result'] = compare_result
+    else:
+        output['verified'] = True
+    data[str(output['local']['timestamp'])] = output  # str makes better dict keys than float
+    with open(jsonfile, 'w') as fp:
+        json.dump(data, fp, sort_keys=True)
+
+    if output['verified']:
+        jsonfile = 'unsigned/verified.json'
+        if os.path.exists(jsonfile):
+            with open(jsonfile) as fp:
+                data = json.load(fp, cls=Decoder, object_pairs_hook=hashabledict)
+        else:
+            data = OrderedDict()
+            data['packages'] = OrderedDict()
+        packageName = output['local']['packageName']
+        if packageName not in data['packages']:
+            data['packages'][packageName] = set()
+        data['packages'][packageName].add(output)
+        with open(jsonfile, 'w') as fp:
+            json.dump(data, fp, cls=Encoder, sort_keys=True)
+
+
 def main():
 
     global options, config
@@ -42,6 +131,8 @@ def main():
     parser.add_argument("appid", nargs='*', help=_("applicationId with optional versionCode in the form APPID[:VERCODE]"))
     parser.add_argument("--reuse-remote-apk", action="store_true", default=False,
                         help=_("Verify against locally cached copy rather than redownloading."))
+    parser.add_argument("--output-json", action="store_true", default=False,
+                        help=_("Output JSON report to file named after APK."))
     options = parser.parse_args()
 
     config = common.read_config(options)
@@ -64,6 +155,7 @@ def main():
     for apkfile in sorted(glob.glob(os.path.join(unsigned_dir, '*.apk'))):
 
         apkfilename = os.path.basename(apkfile)
+        url = 'https://f-droid.org/repo/' + apkfilename
         appid, vercode = common.publishednameinfo(apkfile)
 
         if vercodes and appid not in vercodes:
@@ -79,7 +171,6 @@ def main():
             if not options.reuse_remote_apk or not os.path.exists(remote_apk):
                 if os.path.exists(remote_apk):
                     os.remove(remote_apk)
-                url = 'https://f-droid.org/repo/' + apkfilename
                 logging.info("...retrieving " + url)
                 try:
                     net.download_file(url, dldir=tmp_dir)
@@ -90,10 +181,10 @@ def main():
                         raise FDroidException(_('Downloading {url} failed. {error}')
                                               .format(url=url, error=e))
 
-            compare_result = common.verify_apks(
-                remote_apk,
-                os.path.join(unsigned_dir, apkfilename),
-                tmp_dir)
+            unsigned_apk = os.path.join(unsigned_dir, apkfilename)
+            compare_result = common.verify_apks(remote_apk, unsigned_apk, tmp_dir)
+            if options.output_json:
+                write_json_report(url, remote_apk, unsigned_apk, compare_result)
             if compare_result:
                 raise FDroidException(compare_result)