diff --git a/machines/biotite/default.nix b/machines/biotite/default.nix
index a507675..cf652c8 100644
--- a/machines/biotite/default.nix
+++ b/machines/biotite/default.nix
@@ -1,4 +1,5 @@
 {
+  pkgs,
   lib,
   ...
 }:
@@ -7,6 +8,8 @@
   imports = [
     ./hardware-configurations.nix
     ./services/gotosocial.nix
+    ./services/synapse.nix
+    ./services/restic.nix
   ];
 
   networking.hostName = "biotite";
@@ -43,6 +46,37 @@
   services.caddy.enable = true;
   services.tailscale.enable = true;
 
+  services.postgresql = {
+    enable = true;
+    package = pkgs.postgresql_17;
+    settings = {
+      allow_alter_system = false;
+      # DB Version: 17
+      # OS Type: linux
+      # DB Type: mixed
+      # Total Memory (RAM): 8 GB
+      # CPUs num: 4
+      # Data Storage: ssd
+      max_connections = 100;
+      shared_buffers = "2GB";
+      effective_cache_size = "6GB";
+      maintenance_work_mem = "512MB";
+      checkpoint_completion_target = 0.9;
+      wal_buffers = "16MB";
+      default_statistics_target = 100;
+      random_page_cost = 1.1;
+      effective_io_concurrency = 200;
+      work_mem = "5242kB";
+      huge_pages = "off";
+      min_wal_size = "1GB";
+      max_wal_size = "4GB";
+      max_worker_processes = 4;
+      max_parallel_workers_per_gather = 2;
+      max_parallel_workers = 4;
+      max_parallel_maintenance_workers = 2;
+    };
+  };
+
   users.users.root.hashedPassword = "$y$j9T$NToEZWJBONjSgRnMd9Ur9/$o6n7a9b8eUILQz4d37oiHCCVnDJ8hZTZt.c.37zFfU.";
 
   system.stateVersion = "24.11";
diff --git a/machines/biotite/secrets.yaml b/machines/biotite/secrets.yaml
index 5d8f181..b2ed748 100644
--- a/machines/biotite/secrets.yaml
+++ b/machines/biotite/secrets.yaml
@@ -1,5 +1,10 @@
 gotosocial:
     oidc_client_secret: ENC[AES256_GCM,data:KVQxzs67sohax2h0Y/jjhnbY4fetrdVvWhBGbqgDSGgBC7QazrOmTA++BSRzMmVv,iv:HIRMc56aLanqQRTWH9E0wzzXymImi0pxK/ccPEP8Fcc=,tag:PMhOLeE3mKIIQveRdfpgpA==,type:str]
+synapse:
+    oidc_client_secret: ENC[AES256_GCM,data:TdZF8Bo+h34fn03sPpt7JEqmP8Cwm8V++q9VDvaapMBc3rlkrVu3iDUhQE2DvJri,iv:/QNX+aYUPpDKIqWZ13TLAznR3ZpUPI8rQHrJuqv7R+g=,tag:lcBIpeWiIXK/NV84uuxNiA==,type:str]
+restic:
+    repo_url: ENC[AES256_GCM,data:ZcBMqwEsyc7zyEftJZj4XkKBzUHwlqd6cjX8xVDn9m26jBL7aP5atpnXDRE9FXY4CuAllFyQZyAOQ2L61Nfx+iplL2ADbSoH,iv:fhNODiyoOlZEqYR2O/GsH2IWTPDr3rXSJgWC/EFDLSA=,tag:nZdKKnpiszSiXxdZI1KQ/A==,type:str]
+    repo_password: ENC[AES256_GCM,data:9YDOz1tiyykz6zSXboWtIg==,iv:j96mRLXGuD4NZcC0Nv1yXFbtOlr6UborqclefZ7J94w=,tag:MqhSewK2NuckTJBf7xu+lA==,type:str]
 sops:
     kms: []
     gcp_kms: []
@@ -24,8 +29,8 @@ sops:
             RzBMVDNjS29SUkdRK3dIV01sU0hYR3cK1SbvKAM6Gpsffv3HIi/WtWnCZUBic0AT
             ZRv4pvJBx1oxWsKIHW0t6VrqWMQ+suup8p6dW+h5HE8Z4ciIMrXLEg==
             -----END AGE ENCRYPTED FILE-----
-    lastmodified: "2024-12-02T05:10:32Z"
-    mac: ENC[AES256_GCM,data:ZAdFsjVuk1Fiv+DKmHrc1yu1XQpRDmRHaQhu5hduSZUa1W1cXdTlChvIW5vADFg5tVCjuYptuLvCMW+ZSQeqqG2ntHHZ+IkuovZzKFuc+BIiL/jF2ZzbyJ7X4Wj1GziCScHVxx98dgbpFoufHe6N3wCaHmngo1RYsY5N1RRbRdU=,iv:5IMQ0kOX9UAOm8bcsQRyu6zu8GJjvnHFufCNjY0s9UI=,tag:zBEPSR9DZDpwbCaIka8mXA==,type:str]
+    lastmodified: "2024-12-03T07:38:24Z"
+    mac: ENC[AES256_GCM,data:KMKdwgu9+3DjG1lrQYQEz/jYWsHUBK6RgHRyRKzWG0jTDg30owRpCgnSnX5gHzygmSYSnVRtcTOWzqm5bI7/KJkXBivaqkLqCh6EHnTj+pnAHmeEOAjoOVLOMSCEYvHMf/EuJIL199Hf2G12LtulDJV7Wi5r5Jy8L9odVlYuM9g=,iv:WTeqWdIztScZnXc2hzI7JHO/4ySgqycOp2eN9EPTQpw=,tag:lTMrE5JVVFCIDehXCxJZoQ==,type:str]
     pgp: []
     unencrypted_suffix: _unencrypted
     version: 3.9.1
diff --git a/machines/biotite/services/gotosocial.nix b/machines/biotite/services/gotosocial.nix
index fb26a69..e410a7c 100644
--- a/machines/biotite/services/gotosocial.nix
+++ b/machines/biotite/services/gotosocial.nix
@@ -27,6 +27,7 @@
       oidc-client-id = "gotosocial";
       oidc-link-existing = true;
     };
+    setupPostgresqlDB = true;
     environmentFile = config.sops.templates."gotosocial.env".path;
   };
 
diff --git a/machines/biotite/services/restic.nix b/machines/biotite/services/restic.nix
new file mode 100644
index 0000000..2e53c46
--- /dev/null
+++ b/machines/biotite/services/restic.nix
@@ -0,0 +1,55 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+let
+  sqliteBackup = fromPath: toPath: file: ''
+    mkdir -p ${toPath}
+    ${lib.getExe pkgs.sqlite} ${fromPath} ".backup '${toPath}/${file}'"
+  '';
+in
+{
+  sops.secrets = {
+    "restic/repo_url" = {
+      sopsFile = ../secrets.yaml;
+    };
+    "restic/repo_password" = {
+      sopsFile = ../secrets.yaml;
+    };
+  };
+
+  custom.restic = {
+    enable = true;
+    paths = [
+      "/backup/db"
+      "/backup/var/lib"
+    ];
+    backupPrepareCommand = [
+      ''
+        mkdir -p /backup/var
+        ${pkgs.btrfs-progs}/bin/btrfs subvolume snapshot -r /var/lib /backup/var/lib
+      ''
+    ];
+    backupCleanupCommand = [
+      ''
+        ${pkgs.btrfs-progs}/bin/btrfs subvolume delete /backup/var/lib
+      ''
+    ];
+    btrfsRoots = [ ];
+  };
+
+  services.postgresqlBackup = {
+    enable = true;
+    compression = "zstd";
+    compressionLevel = 9;
+    location = "/backup/db/postgresql";
+  };
+
+  services.restic.backups.${config.networking.hostName} = {
+    extraBackupArgs = [
+      "--limit-upload=1024"
+    ];
+  };
+}
diff --git a/machines/biotite/services/synapse.nix b/machines/biotite/services/synapse.nix
new file mode 100644
index 0000000..7d4712b
--- /dev/null
+++ b/machines/biotite/services/synapse.nix
@@ -0,0 +1,113 @@
+{ config, pkgs, ... }:
+let
+  port-synapse = 6823;
+in
+{
+  sops.secrets."synapse/oidc_client_secret" = {
+    owner = "matrix-synapse";
+  };
+
+  nixpkgs.config.permittedInsecurePackages = [
+    "olm-3.2.16"
+  ];
+
+  services.postgresql = {
+    # Not using ensure here because LC_COLLATE and LC_CTYPE must be provided
+    # at db creation
+    initialScript = pkgs.writeText "synapse-init.sql" ''
+      CREATE ROLE "matrix-synapse" WITH LOGIN PASSWORD 'synapse';
+      CREATE DATABASE "matrix-synapse" WITH OWNER "matrix-synapse"
+        TEMPLATE template0
+        LC_COLLATE = "C"
+        LC_CTYPE = "C";
+    '';
+  };
+
+  services.matrix-synapse = {
+    enable = true;
+    settings = {
+      server_name = "xiny.li";
+      public_baseurl = "https://synapse.xiny.li";
+      database = {
+        name = "psycopg2";
+        args = {
+          user = "matrix-synapse";
+        };
+      };
+      listeners = [
+        {
+          bind_addresses = [
+            "127.0.0.1"
+          ];
+          port = port-synapse;
+          resources = [
+            {
+              compress = true;
+              names = [
+                "client"
+                "federation"
+              ];
+            }
+          ];
+          tls = false;
+          type = "http";
+          x_forwarded = true;
+        }
+      ];
+      experimental_features = {
+        # Room summary api
+        msc3266_enabled = true;
+        # Removing account data
+        msc3391_enabled = true;
+        # Thread notifications
+        msc3773_enabled = true;
+        # Remotely toggle push notifications for another client
+        msc3881_enabled = true;
+        # Remotely silence local notifications
+        msc3890_enabled = true;
+        # Remove legacy mentions
+        msc4210_enabled = true;
+      };
+      oidc_providers = [
+        {
+          idp_id = "Kanidm";
+          idp_name = "auth.xinyang.life";
+          issuer = "https://auth.xinyang.life/oauth2/openid/synapse";
+          authorization_endpoint = "https://auth.xinyang.life/ui/oauth2";
+          token_endpoint = "https://auth.xinyang.life/oauth2/token";
+          userinfo_endpoint = "https://auth.xinyang.life/oauth2/openid/synapse/userinfo";
+          client_id = "synapse";
+          client_secret_path = config.sops.secrets."synapse/oidc_client_secret".path;
+          scopes = [
+            "openid"
+            "profile"
+          ];
+          allow_existing_users = true;
+          backchannel_logout_enabled = true;
+          user_mapping_provider.config = {
+            confirm_localpart = true;
+            localpart_template = "{{ user.preferred_username }}";
+            display_name_template = "{{ user.name }}";
+          };
+        }
+      ];
+    };
+  };
+
+  services.caddy = {
+    virtualHosts."https://xiny.li".extraConfig = ''
+      header /.well-known/matrix/* Content-Type application/json
+      header /.well-known/matrix/* Access-Control-Allow-Origin *
+      respond /.well-known/matrix/server `{"m.server":"synapse.xiny.li:443"}`
+      respond /.well-known/matrix/client `{"m.homeserver":{"base_url":"https://synapse.xiny.li/"}}`
+    '';
+    virtualHosts."https://synapse.xiny.li".extraConfig = ''
+      reverse_proxy /_matrix/* 127.0.0.1:${toString port-synapse}
+      reverse_proxy /_synapse/client/* 127.0.0.1:${toString port-synapse}
+    '';
+  };
+
+  networking.firewall.allowedTCPPorts = [
+    443
+  ];
+}
diff --git a/machines/massicot/kanidm-provision.nix b/machines/massicot/kanidm-provision.nix
index 8a95a99..1e6927a 100644
--- a/machines/massicot/kanidm-provision.nix
+++ b/machines/massicot/kanidm-provision.nix
@@ -45,6 +45,9 @@
       miniflux-users = {
         members = [ "xin" ];
       };
+      synapse-users = {
+        members = [ "xin" ];
+      };
       idm_people_self_mail_write = {
         members = [ ];
       };
@@ -211,6 +214,17 @@
           };
         };
       };
+      synapse = {
+        displayName = "Synapse";
+        originUrl = "https://synapse.xiny.li/_synapse/client/oidc/callback";
+        originLanding = "https://synapse.xiny.li/";
+        scopeMaps = {
+          synapse-users = [
+            "openid"
+            "profile"
+          ];
+        };
+      };
     };
   };
 }