--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -2616,16 +2616,21 @@ pref("services.blocklist.plugins.collect
 pref("services.blocklist.plugins.checked", 0);
 pref("services.blocklist.pinning.enabled", true);
 pref("services.blocklist.pinning.bucket", "pinning");
 pref("services.blocklist.pinning.collection", "pins");
 pref("services.blocklist.pinning.checked", 0);
 pref("services.blocklist.gfx.collection", "gfx");
 pref("services.blocklist.gfx.checked", 0);
 
+// Fonts downloading for fingerprinting resistance via settings server (Kinto)
+pref("privacy.resistFingerprinting.fonts.bucket", "fingerprinting-defenses");
+pref("privacy.resistFingerprinting.fonts.collection", "fonts");
+pref("privacy.resistFingerprinting.fonts.checked", 0);
+
 // Controls whether signing should be enforced on signature-capable blocklist
 // collections.
 pref("services.blocklist.signing.enforced", true);
 
 // Enable blocklists via the services settings mechanism
 pref("services.blocklist.update_enabled", true);
 
 

--- a/services/common/blocklist-clients.js
+++ b/services/common/blocklist-clients.js
@@ -3,17 +3,18 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 "use strict";
 
 this.EXPORTED_SYMBOLS = ["AddonBlocklistClient",
                          "GfxBlocklistClient",
                          "OneCRLBlocklistClient",
                          "PinningBlocklistClient",
-                         "PluginBlocklistClient"];
+                         "PluginBlocklistClient",
+                         "FontsRFPClient"];
 
 const { classes: Cc, interfaces: Ci, utils: Cu } = Components;
 
 Cu.import("resource://gre/modules/Services.jsm");
 Cu.import("resource://gre/modules/XPCOMUtils.jsm");
 const { OS } = Cu.import("resource://gre/modules/osfile.jsm", {});
 Cu.importGlobalProperties(["fetch"]);
 
@@ -42,16 +43,21 @@ const PREF_BLOCKLIST_PLUGINS_CHECKED_SEC
 const PREF_BLOCKLIST_PINNING_ENABLED         = "services.blocklist.pinning.enabled";
 const PREF_BLOCKLIST_PINNING_BUCKET          = "services.blocklist.pinning.bucket";
 const PREF_BLOCKLIST_PINNING_COLLECTION      = "services.blocklist.pinning.collection";
 const PREF_BLOCKLIST_PINNING_CHECKED_SECONDS = "services.blocklist.pinning.checked";
 const PREF_BLOCKLIST_GFX_COLLECTION          = "services.blocklist.gfx.collection";
 const PREF_BLOCKLIST_GFX_CHECKED_SECONDS     = "services.blocklist.gfx.checked";
 const PREF_BLOCKLIST_ENFORCE_SIGNING         = "services.blocklist.signing.enforced";
 
+// Prefs for font fingerprinting resistance.
+const PREF_RFP_FONTS_BUCKET          = "privacy.resistFingerprinting.fonts.bucket";
+const PREF_RFP_FONTS_CHECKED_SECONDS = "privacy.resistFingerprinting.fonts.checked";
+const PREF_RFP_FONTS_COLLECTION      = "privacy.resistFingerprinting.fonts.collection";
+
 const INVALID_SIGNATURE = "Invalid content/signature";
 
 // This was the default path in earlier versions of
 // FirefoxAdapter, so for backwards compatibility we maintain this
 // filename, even though it isn't descriptive of who is using it.
 const KINTO_STORAGE_PATH = "kinto.sqlite";
 
 
@@ -433,16 +439,39 @@ async function updateJSONBlocklist(filen
     // Notify change to `nsBlocklistService`
     const eventData = {filename};
     Services.cpmm.sendAsyncMessage("Blocklist:reload-from-disk", eventData);
   } catch (e) {
     Cu.reportError(e);
   }
 }
 
+/**
+ * Write the list of fonts for fingerprinting resistance into a JSON file and
+ * notify nsRFPService to download fonts if necessary.
+ *
+ * @param {String} filename  path relative to profile dir.
+ * @param {Object} records   current records in the local db.
+ */
+async function updateFontList(filename, records) {
+  const path = OS.Path.join(OS.Constants.Path.profileDir, filename);
+  const blocklistFolder = OS.Path.dirname(path);
+
+  await OS.File.makeDir(blocklistFolder, {from: OS.Constants.Path.profileDir});
+
+  const serialized = JSON.stringify({data: records}, null, 2);
+
+  try {
+    await OS.File.writeAtomic(path, serialized, {tmpPath: path + ".tmp"});
+    Services.obs.notifyObservers(null, "resist-fingerprinting:download-fonts");
+  } catch (e) {
+    Cu.reportError(e);
+  }
+}
+
 this.OneCRLBlocklistClient = new BlocklistClient(
   Services.prefs.getCharPref(PREF_BLOCKLIST_ONECRL_COLLECTION),
   PREF_BLOCKLIST_ONECRL_CHECKED_SECONDS,
   updateCertBlocklist,
   Services.prefs.getCharPref(PREF_BLOCKLIST_BUCKET),
   "onecrl.content-signature.mozilla.org"
 );
 
@@ -469,8 +498,16 @@ this.PluginBlocklistClient = new Blockli
 
 this.PinningPreloadClient = new BlocklistClient(
   Services.prefs.getCharPref(PREF_BLOCKLIST_PINNING_COLLECTION),
   PREF_BLOCKLIST_PINNING_CHECKED_SECONDS,
   updatePinningList,
   Services.prefs.getCharPref(PREF_BLOCKLIST_PINNING_BUCKET),
   "pinning-preload.content-signature.mozilla.org"
 );
+
+this.FontsRFPClient = new BlocklistClient(
+  Services.prefs.getCharPref(PREF_RFP_FONTS_COLLECTION),
+  PREF_RFP_FONTS_CHECKED_SECONDS,
+  (records) => updateFontList(this.FontsRFPClient.filename, records),
+  Services.prefs.getCharPref(PREF_RFP_FONTS_BUCKET),
+  "fingerprinting-defenses.content-signature.mozilla.org"
+);

--- a/services/common/blocklist-updater.js
+++ b/services/common/blocklist-updater.js
@@ -27,16 +27,17 @@ const TELEMETRY_HISTOGRAM_KEY = "setting
 XPCOMUtils.defineLazyGetter(this, "gBlocklistClients", function() {
   const BlocklistClients = Cu.import("resource://services-common/blocklist-clients.js", {});
   return {
     [BlocklistClients.OneCRLBlocklistClient.collectionName]: BlocklistClients.OneCRLBlocklistClient,
     [BlocklistClients.AddonBlocklistClient.collectionName]: BlocklistClients.AddonBlocklistClient,
     [BlocklistClients.GfxBlocklistClient.collectionName]: BlocklistClients.GfxBlocklistClient,
     [BlocklistClients.PluginBlocklistClient.collectionName]: BlocklistClients.PluginBlocklistClient,
     [BlocklistClients.PinningPreloadClient.collectionName]: BlocklistClients.PinningPreloadClient,
+    [BlocklistClients.FontsRFPClient.collectionName]: BlocklistClients.FontsRFPClient,
   };
 });
 
 // Add a blocklist client for testing purposes. Do not use for any other purpose
 this.addTestBlocklistClient = (name, client) => { gBlocklistClients[name] = client; };
 
 
 async function pollChanges(url, lastEtag) {