diff --git a/lib/types/backup-types.js b/lib/types/backup-types.js
new file mode 100644
--- /dev/null
+++ b/lib/types/backup-types.js
@@ -0,0 +1,30 @@
+// @flow
+
+import type { UserStore } from './user-types.js';
+
+export type UserKeys = {
+  +backupDataKey: string,
+  +ed25519: string,
+};
+
+export type UserData = {
+  +userStore: UserStore,
+};
+
+export type BackupAuth = {
+  +userID: string,
+  +accessToken: string,
+  +deviceID: string,
+};
+
+export type Backup = {
+  +backupID: string,
+  +userKeys: UserKeys,
+  +userData: UserData,
+};
+
+export type BackupEncrypted = {
+  +backupID: string,
+  +userKeys: Uint8Array,
+  +userData: Uint8Array,
+};