diff --git a/daemon.py b/daemon.py
index a9ecabc9d..4f25f5e7e 100644
--- a/daemon.py
+++ b/daemon.py
@@ -837,6 +837,12 @@ def run_daemon(accounts_data_dir: str,
     # cache for automatic content warnings
     httpd.auto_cw_cache = load_auto_cw_cache(base_dir)
 
+    # loads a catalog of http header fields
+    headers_catalog_fieldname = data_dir(base_dir) + '/headers_catalog.json'
+    httpd.headers_catalog = {}
+    if os.path.isfile(headers_catalog_fieldname):
+        httpd.headers_catalog = load_json(headers_catalog_fieldname)
+
     # list of websites which are currently down
     httpd.sites_unavailable = load_unavailable_sites(base_dir)
 
diff --git a/daemon_get.py b/daemon_get.py
index 13e71d766..cfbbb8f97 100644
--- a/daemon_get.py
+++ b/daemon_get.py
@@ -67,6 +67,7 @@ from daemon_utils import has_accept
 from daemon_utils import show_person_options
 from daemon_utils import is_authorized
 from daemon_utils import get_user_agent
+from httpheaders import update_headers_catalog
 from httpheaders import set_headers_etag
 from httpheaders import login_headers
 from httpheaders import redirect_headers
@@ -243,6 +244,11 @@ def daemon_http_get(self) -> None:
 
     calling_domain = self.server.domain_full
 
+    # record header fields encountered
+    update_headers_catalog(self.server.base_dir,
+                           self.server.headers_catalog,
+                           self.headers)
+
     if self.headers.get('Server'):
         if self.headers['Server'] in corp_servers():
             print('GET HTTP Corporate leech bounced: ' +
diff --git a/daemon_post.py b/daemon_post.py
index c9a0929e0..14aae2c9b 100644
--- a/daemon_post.py
+++ b/daemon_post.py
@@ -34,6 +34,7 @@ from httpcodes import http_400
 from httpcodes import http_402
 from httpcodes import http_404
 from httpcodes import http_503
+from httpheaders import update_headers_catalog
 from httpheaders import redirect_headers
 from daemon_utils import get_user_agent
 from daemon_utils import post_to_outbox
@@ -87,6 +88,10 @@ def daemon_http_post(self) -> None:
               ' path: ' + self.path + ' busy: ' +
               str(self.server.postreq_busy))
 
+    update_headers_catalog(self.server.base_dir,
+                           self.server.headers_catalog,
+                           self.headers)
+
     calling_domain = self.server.domain_full
     if self.headers.get('Host'):
         calling_domain = decoded_host(self.headers['Host'])
diff --git a/httpheaders.py b/httpheaders.py
index 1c6b6d5b6..9054381b7 100644
--- a/httpheaders.py
+++ b/httpheaders.py
@@ -12,6 +12,8 @@ import urllib.parse
 from hashlib import md5
 from utils import string_contains
 from utils import get_instance_url
+from utils import data_dir
+from utils import save_json
 
 
 def login_headers(self, file_format: str, length: int,
@@ -205,3 +207,20 @@ def set_headers_etag(self, media_filename: str, file_format: str,
         self.send_header('last-modified', last_modified)
     self.send_header('accept-ranges', 'bytes')
     self.end_headers()
+
+
+def update_headers_catalog(base_dir: str, headers_catalog: {},
+                           headers: {}) -> None:
+    """Creates a catalog of headers
+    This allows us to spot anything unexpected for later investigation
+    """
+    headers_catalog_fieldname = data_dir(base_dir) + '/headers_catalog.json'
+    changed = False
+    for fieldname, fieldvalue in headers.items():
+        if fieldname in headers_catalog:
+            continue
+        headers_catalog[fieldname] = fieldvalue
+        changed = True
+
+    if changed:
+        save_json(headers_catalog, headers_catalog_fieldname)