diff --git a/frontend/src/components/MainMap.tsx b/frontend/src/components/MainMap.tsx
index 3fd40c1..98ef11f 100644
--- a/frontend/src/components/MainMap.tsx
+++ b/frontend/src/components/MainMap.tsx
@@ -43,9 +43,20 @@ function unwrapLon(ring: [number, number][]): [number, number][] {
 }
 
 const CARTO_LIGHT = 'https://{s}.basemaps.cartocdn.com/light_all/{z}/{x}/{y}{r}.png';
-const OSM = 'https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png';
 const CARTO_ATTR = '© OpenStreetMap © CARTO';
-const OSM_ATTR = '© OpenStreetMap contributors';
+
+// NOT tile.openstreetmap.org. Those are OpenStreetMap's VOLUNTEER-run servers,
+// and their usage policy does not cover a desktop application handed to an
+// unbounded number of operators — they blocked OpsLog for it, and every user's
+// map filled with "Access blocked / 403" tiles at once.
+//
+// The replacements are tile services whose terms do cover redistributed apps,
+// with no API key: Carto (whose tiles are OSM-derived, hence the attribution
+// still credits OpenStreetMap) and Esri. Anything added here later must be
+// checked the same way — a free tile URL is not the same thing as a tile URL we
+// are allowed to ship.
+const ESRI_STREET = 'https://server.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer/tile/{z}/{y}/{x}';
+const ESRI_STREET_ATTR = 'Tiles © Esri — Source: Esri, HERE, Garmin, © OpenStreetMap contributors';
 
 // Selectable basemaps for the world (great-circle) map. All key-free and all
 // LABELLED (country/continent names). `labelsUrl` adds a transparent place-name
@@ -55,7 +66,7 @@ const BASEMAPS: Record<BasemapKey, { label: string; url: string; attr: string; s
   light:     { label: 'Light',     url: CARTO_LIGHT, attr: CARTO_ATTR, subdomains: 'abcd' },
   voyager:   { label: 'Voyager',   url: 'https://{s}.basemaps.cartocdn.com/rastertiles/voyager/{z}/{x}/{y}{r}.png',
                attr: CARTO_ATTR, subdomains: 'abcd' },
-  street:    { label: 'Street',    url: OSM, attr: OSM_ATTR },
+  street:    { label: 'Street',    url: ESRI_STREET, attr: ESRI_STREET_ATTR },
   satellite: { label: 'Satellite', url: 'https://server.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer/tile/{z}/{y}/{x}',
                attr: 'Tiles &copy; Esri — Source: Esri, Maxar, Earthstar Geographics',
                labelsUrl: 'https://server.arcgisonline.com/ArcGIS/rest/services/Reference/World_Boundaries_and_Places/MapServer/tile/{z}/{y}/{x}' },
@@ -416,7 +427,14 @@ export function LocatorMap({ toGrid, toLabel }: LocatorProps) {
     if (locatorRef.current && !locatorMap.current) {
       const m = L.map(locatorRef.current, { zoomControl: true, attributionControl: true })
         .setView([20, 0], 2);
-      L.tileLayer(OSM, { attribution: OSM_ATTR, maxZoom: 19 }).addTo(m);
+      // Same restraint as the world map: fetch on idle, not mid-pan, and keep a
+      // single ring of buffer tiles. Requesting tiles as fast as the pointer
+      // moves is what gets an app blocked, and the next provider is under no
+      // more obligation to tolerate it than the last one was.
+      L.tileLayer(CARTO_LIGHT, {
+        attribution: CARTO_ATTR, subdomains: 'abcd', maxZoom: 19,
+        updateWhenIdle: true, updateWhenZooming: false, keepBuffer: 1,
+      }).addTo(m);
       locatorOverlay.current = L.layerGroup().addTo(m);
       locatorMap.current = m;
     }