diff --git a/src/matrix-client.vala b/src/matrix-client.vala
index 4fc4ecb..ee6de07 100644
--- a/src/matrix-client.vala
+++ b/src/matrix-client.vala
@@ -247,4 +247,23 @@ public interface Matrix.Client : GLib.Object {
          SendCallback? cb,
          out ulong txn_id)
         throws Matrix.Error;
+
+    /*
+     * Save the state of the client. Implementors can choose what they
+     * actually save, and in what format.
+     *
+     * @param filename the name of the file to save state to
+     */
+    public abstract void
+    save_state(string filename)
+        throws Matrix.Error, GLib.Error;
+
+    /**
+     * Load the state of the client, as saved by save_state().
+     *
+     * @param filename the name of the file to load state from
+     */
+    public abstract void
+    load_state(string filename)
+        throws Matrix.Error, GLib.Error;
 }
diff --git a/src/matrix-http-api.vala b/src/matrix-http-api.vala
index b26142a..0f1c54d 100644
--- a/src/matrix-http-api.vala
+++ b/src/matrix-http-api.vala
@@ -87,7 +87,7 @@ public class Matrix.HTTPAPI : GLib.Object, Matrix.API {
             _soup_session.ssl_strict = value;
         }
     }
-    private string? _user_id;
+    protected string? _user_id;
     public string? user_id {
         get {
             return _user_id;
@@ -97,7 +97,7 @@ public class Matrix.HTTPAPI : GLib.Object, Matrix.API {
     }
     public string? token { get; set; default = null; }
     public string? refresh_token { get; set; default = null; }
-    private string? _homeserver;
+    protected string? _homeserver;
     public string? homeserver {
         get {
             return _homeserver;
diff --git a/src/matrix-http-client.vala b/src/matrix-http-client.vala
index 674a470..6258512 100644
--- a/src/matrix-http-client.vala
+++ b/src/matrix-http-client.vala
@@ -564,4 +564,85 @@ public class Matrix.HTTPClient : Matrix.HTTPAPI, Matrix.Client {
                     evt_root.get_member("content"));
         }
     }
+
+    public void
+    save_state(string filename)
+        throws Matrix.Error, GLib.Error
+    {
+        var root = new Json.Object();
+
+        root.set_string_member("base_url", base_url);
+
+        root.set_boolean_member("validate_certificate", validate_certificate);
+
+        if (user_id != null) {
+            root.set_string_member("user_id", user_id);
+        }
+
+        if (homeserver != null) {
+            root.set_string_member("homeserver_name", homeserver);
+        }
+
+        if (token != null) {
+            root.set_string_member("access_token", token);
+        }
+
+        if (refresh_token != null) {
+            root.set_string_member("refresh_token", refresh_token);
+        }
+
+        var node = new Json.Node(Json.NodeType.OBJECT);
+        node.set_object(root);
+
+        var generator = new Json.Generator();
+        generator.set_root(node);
+        generator.to_file(filename);
+    }
+
+    public void
+    load_state(string filename)
+        throws Matrix.Error, GLib.Error
+    {
+        var parser = new Json.Parser();
+
+        parser.load_from_file(filename);
+        Json.Node? node = parser.get_root();
+
+        if (node.get_node_type() != Json.NodeType.OBJECT) {
+            throw new Matrix.Error.INVALID_FORMAT(
+                    "Save data must be a JSON object.");
+        }
+
+        var root = node.get_object();
+
+        if ((node = root.get_member("base_url")) == null) {
+            throw new Matrix.Error.INVALID_FORMAT(
+                    "Save data has no base_url key");
+        }
+
+        base_url = node.get_string();
+
+        if ((node = root.get_member("validate_certificate")) == null) {
+            throw new Matrix.Error.INVALID_FORMAT(
+                    "Save data has no validate_certificate key");
+        }
+
+        validate_certificate = node.get_boolean();
+
+        if ((node = root.get_member("user_id")) != null) {
+            _user_id = node.get_string();
+        }
+
+        if ((node = root.get_member("homeserver_name")) != null) {
+            _homeserver = node.get_string();
+        }
+
+        if ((node = root.get_member("access_token")) != null) {
+            token = node.get_string();
+        }
+
+        if ((node = root.get_member("refresh_token")) != null) {
+            refresh_token = node.get_string();
+        }
+    }
 }