diff --git a/include/api.hpp b/include/api.hpp
new file mode 100644
index 0000000..d7c3fa5
--- /dev/null
+++ b/include/api.hpp
@@ -0,0 +1,37 @@
+/*  This file is part of mastodonpp.
+ *  Copyright © 2020 tastytea <tastytea@tastytea.de>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as published by
+ *  the Free Software Foundation, version 3.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef MASTODONPP_API_HPP
+#define MASTODONPP_API_HPP
+
+namespace mastodonpp::API
+{
+
+/*!
+ *  @brief  A list of all v1 API calls.
+ *
+ *  The original `/` are substituted by `_`.
+ *
+ *  @since  0.1.0
+ */
+enum class v1
+{
+    instance
+};
+
+} // namespace mastodonpp::API
+
+#endif  // MASTODONPP_API_HPP
diff --git a/include/mastodonpp.hpp b/include/mastodonpp.hpp
index 0b7afc4..e48c093 100644
--- a/include/mastodonpp.hpp
+++ b/include/mastodonpp.hpp
@@ -17,6 +17,7 @@
 #ifndef MASTODONPP_HPP
 #define MASTODONPP_HPP
 
+#include "api.hpp"
 #include "instance.hpp"
 #include "return_types.hpp"