diff --git a/README.md b/README.md
index 6f1bf04..44fa9d7 100644
--- a/README.md
+++ b/README.md
@@ -666,6 +666,16 @@ curl -H "Authorization: Bearer $TOKEN" http://10.0.0.4:7081/config
 | `ipsec` | `connections` and `sas`: one object per connection and per IKE SA, read from `swanctl --list-conns --pretty` and `swanctl --list-sas --pretty`, with the connection's name under `name` and swanctl's keys and string values |
 | `wireguard` | The public key and port of `wg0`, and each peer's public key, endpoint, allowed IPs, handshake age and traffic; no private or preshared key |
 | `docker` | `docker.exposed_ports` and the rules of the `VPN-ROUTER-DOCKER` chain |
+| `postgresql` | `clusters`: each PostgreSQL cluster of `pg_lsclusters` with its version, name, port, status and data directory, and for one that is online its `settings`: `server_version`, `listen_addresses`, `port`, `max_connections`, `shared_buffers`, `effective_cache_size`, `work_mem`, `password_encryption`, `ssl` and `timezone`; `null` when `pg_lsclusters` fails |
+
+### The /postgresql page
+
+`/postgresql`, with the same token as `/config`, shows the databases of the PostgreSQL clusters on the
+router:
+
+- **Content:** `clusters` lists each cluster with its version, name, port and status, its `databases` (name, owner, encoding and size in bytes, `pg_database_size`) and their total `size`.
+- **A cluster that is not online:** `databases` and `size` are `null`.
+- **Collection:** the web service reads it with `psql` as the `postgres` user at each request.
 
 ### The /users API
 
diff --git a/debian-package/debian/changelog b/debian-package/debian/changelog
index df43874..0508e63 100644
--- a/debian-package/debian/changelog
+++ b/debian-package/debian/changelog
@@ -1,3 +1,15 @@
+vpn-router (0.17.0-1) unstable; urgency=medium
+
+  feature: /config shows the router's PostgreSQL clusters and their settings, and /postgresql their databases with their sizes.
+
+  * /config has a postgresql section: each cluster of pg_lsclusters with
+    its version, name, port, status and data directory, and the main
+    settings of each online cluster.
+  * /postgresql, protected like /config, lists the databases of each
+    online cluster with owner, encoding and size, and the total size.
+
+ -- Slawomir Koszewski <slawek@koszewscy.waw.pl>  Sun, 25 Oct 2026 21:00:00 +0200
+
 vpn-router (0.16.0-1) unstable; urgency=medium
 
   feature: the router keeps its metrics in PostgreSQL, serves them for an OpenTelemetry Collector and pushes them over OTLP.
diff --git a/debian-package/src/usr/lib/vpn-router/web b/debian-package/src/usr/lib/vpn-router/web
index 84debb1..f6a0333 100644
--- a/debian-package/src/usr/lib/vpn-router/web
+++ b/debian-package/src/usr/lib/vpn-router/web
@@ -21,8 +21,11 @@ Pages:
   /metrics/history
            the metrics the metrics service keeps, for a view: hour, day, month or year (see
            metrics_history())
+  /postgresql
+           the databases of each PostgreSQL cluster on the router with their sizes, as JSON (see
+           postgresql_databases()); /config has the clusters' settings
 
-/config, /metrics/history, /users, /groups and /account need an HS256 JWT in an Authorization: Bearer header signed
+/config, /metrics/history, /postgresql, /users, /groups and /account need an HS256 JWT in an Authorization: Bearer header signed
 with vpnrouter_auth.WEB_KEY (see vpnrouter_auth.verify). A token of /auth names a user in sub;
 /account serves that user, and the other paths need a member of vpnrouter_users.ADMIN_GROUP. A
 token of vpn-router-token has the admin claim and names no user; it may call every path but
@@ -101,6 +104,10 @@ TAILWIND = 'https://cdn.jsdelivr.net/npm/@tailwindcss/browser@4'
 #: Seconds after which the status page in a browser reloads itself.
 REFRESH_SECONDS = 60
 
+#: The PostgreSQL settings /config shows for each cluster.
+POSTGRESQL_SETTINGS = ('server_version', 'listen_addresses', 'port', 'max_connections', 'shared_buffers',
+                       'effective_cache_size', 'work_mem', 'password_encryption', 'ssl', 'timezone')
+
 #: The largest request body accepted, in bytes.
 BODY_LIMIT = 4096
 
@@ -265,6 +272,65 @@ def wireguard_details():
     }
 
 
+def postgresql_query(cluster, sql):
+    """The JSON value an SQL statement answers on a cluster (version/name), run by psql as postgres, or None when it fails."""
+    result = run('runuser', '-u', 'postgres', '--', 'psql', '--cluster', cluster, '-X', '-q', '-t', '-A',
+                 '-v', 'ON_ERROR_STOP=1', '-d', 'postgres', '-c', sql)
+    if result is None or result.returncode != 0:
+        return None
+    try:
+        return json.loads(result.stdout)
+    except ValueError:
+        return None
+
+
+def postgresql_clusters_of():
+    """The PostgreSQL clusters of pg_lsclusters, each with version, name, port, status and data_directory, or None when it fails."""
+    lines = lines_of('pg_lsclusters', '--no-header')
+    if lines is None:
+        return None
+    clusters = []
+    for line in lines:
+        fields = line.split()
+        if len(fields) >= 6:
+            clusters.append({'version': fields[0], 'name': fields[1], 'port': int(fields[2]) if fields[2].isdigit() else None,
+                             'status': fields[3], 'data_directory': fields[5]})
+    return clusters
+
+
+def postgresql_configuration():
+    """The PostgreSQL clusters on the router with the settings of POSTGRESQL_SETTINGS of each one that is online (None
+    for one that is not), or None when pg_lsclusters fails."""
+    clusters = postgresql_clusters_of()
+    if clusters is None:
+        return None
+    names = ', '.join(f"'{name}'" for name in POSTGRESQL_SETTINGS)
+    for cluster in clusters:
+        cluster['settings'] = postgresql_query(
+            f"{cluster['version']}/{cluster['name']}",
+            f'SELECT json_object_agg(name, current_setting(name) ORDER BY name) FROM pg_settings WHERE name IN ({names})',
+        ) if cluster['status'].startswith('online') else None
+    return {'clusters': clusters}
+
+
+def postgresql_databases():
+    """What /postgresql shows: the PostgreSQL clusters on the router, each with its databases (name, owner, encoding and
+    size in bytes) and their total size, None for a cluster that is not online; clusters is None when pg_lsclusters fails."""
+    clusters = postgresql_clusters_of()
+    if clusters is None:
+        return {'clusters': None}
+    for cluster in clusters:
+        databases = postgresql_query(
+            f"{cluster['version']}/{cluster['name']}",
+            "SELECT coalesce(json_agg(json_build_object('name', datname, 'owner', pg_get_userbyid(datdba), "
+            "'encoding', pg_encoding_to_char(encoding), 'size', pg_database_size(oid)) ORDER BY datname), '[]') "
+            'FROM pg_database',
+        ) if cluster['status'].startswith('online') else None
+        cluster['databases'] = databases
+        cluster['size'] = sum(database['size'] for database in databases) if isinstance(databases, list) else None
+    return {'clusters': clusters}
+
+
 def details(state):
     """What /config shows: the configuration without its secrets, and what the router resolved and runs."""
     configuration = state.get('configuration', {})
@@ -280,6 +346,7 @@ def details(state):
             'exposed_ports': configuration.get('docker', {}).get('exposed_ports', []),
             'rules': lines_of('iptables', '-S', 'VPN-ROUTER-DOCKER'),
         },
+        'postgresql': postgresql_configuration(),
     }
 
 
@@ -648,7 +715,7 @@ class Handler(BaseHTTPRequestHandler):
         if self.command not in ('GET', 'HEAD'):
             self.close_connection = True
         directory = next((name for name in ('users', 'groups', 'account') if path == f'/{name}' or path.startswith(f'/{name}/')), None)
-        protected = path in ('/config', '/metrics/history') or directory is not None
+        protected = path in ('/config', '/metrics/history', '/postgresql') or directory is not None
         signing = path in ('/auth', '/auth/refresh', '/auth/logout')
         state = current() if protected or signing else {}
         claims = self.claims(state['key']) if protected and state['key'] else None
@@ -675,6 +742,8 @@ class Handler(BaseHTTPRequestHandler):
             body = json.dumps({'error': refused[1]}, indent=2).encode() + b'\n'
         elif path == '/config' and self.command in ('GET', 'HEAD'):
             body, kind, code = json.dumps(details(state), indent=2).encode() + b'\n', 'application/json', 200
+        elif path == '/postgresql' and self.command in ('GET', 'HEAD'):
+            body, kind, code = json.dumps(postgresql_databases(), indent=2).encode() + b'\n', 'application/json', 200
         elif path == '/metrics/history' and self.command in ('GET', 'HEAD'):
             query = urllib.parse.parse_qs(urllib.parse.urlsplit(self.path).query)
             code, document = metrics_history(query.get('range', ['hour'])[0])