{ config, pkgs, ... }: {
 # https://github.com/NixOS/nixpkgs/issues/21244 
  pkgs.firefox.override (args: args // {
    extraPrefs = ''
      lockPref("extension.pocket.enabled", false);
      lockPref("toolkit.telemetry.pioneer-new-studies-availble", false);
      lockPref("datareporting.healthreport.uploadEnabled", false);
      lockPref("datareporting.healthreport.infoURL", null);
      lockPref("toolkit.telemetry.server", null);
      lockPref("browser.newtabpage.activity-stream.feeds.telemetry", false);
      lockPref("browser.newtabpage.activity-stream.telemetry", false);
      lockPref("browser.ping-centre.telemetry", false);
      lockPref("toolkit.telemetry.enabled", false);
      lockPref("toolkit.telemetry.firstShutdownPing.enabled", false);
      lockPref("toolkit.telemetry.hybridContent.enabled", false);
      lockPref("toolkit.telemetry.newProfilePing.enabled", false);
      lockPref("toolkit.telemetry.shutdownPingSender.enabled", false);
      lockPref("toolkit.telemetry.updatePing.enabled", false);
      lockPref("toolkit.telemetry.reportingpolicy.firstRun", false);
      lockPref("toolkit.telemetry.unified", false);
      lockPref("toolkit.telemetry.archive.enabled", false);
      lockPref("devtools.onboarding.telemetry.logged", false);
      lockPref("toolkit.telemetry.bhrPing.enabled", false);
      lockPref("datareporting.policy.dataSubmissionEnabled", false);
      lockPref("datareporting.sessions.current.clean", true);
      lockPref("browser.startup.homepage", https://dir.sysctl.io);
      lockPref("browser.search.region", US);
      lockPref("browser.search.isUS", false;
      lockPref("distribution.searchplugins.defaultLocale", en-US);
      lockPref("general.useragent.locale", en-US);
      lockPref("browser.bookmarks.showMobileBookmarks", false);
      lockPref("browser.newtabpage.enabled", false);
      lockPref("services.sync.prefs.sync.browser.newtabpage.enabled", false);
    ''
  };
   
   programs.firefox = {
    enable = true;

    profiles.default = {
      isDefault = true;
      name = "default";

      # https://nur.nix-community.org/repos/rycee/
      extensions =  with pkgs.nur.repos.rycee.firefox-addons; [
        privacy-badger
        decentraleyes
        darkreader
        ublock-origin
        privacy-redirect
        link-cleaner
        demodal
      ];

      search.default = "DuckDuckGo";
      search.force = true;
      search.order = [ "DuckDuckGo" ];
      search.engines = {
        "Nix Packages" = {
          urls = [{
            template = "https://search.nixos.org/packages";
            params = [
              { name = "type"; value = "packages"; }
              { name = "query"; value = "{searchTerms}"; }
            ];
          }];

          icon = "${pkgs.nixos-icons}/share/icons/hicolor/scalable/apps/nix-snowflake.svg";
          definedAliases = [ "@np" ];
        };

        "NixOS Wiki" = {
          urls = [{ template = "https://nixos.wiki/index.php?search={searchTerms}"; }];
          iconUpdateURL = "https://nixos.wiki/favicon.png";
          updateInterval = 24 * 60 * 60 * 1000; # every day
          definedAliases = [ "@nw" ];
        };
      };
    };
  };
}