diff --git a/gui/src/data.odin b/gui/src/data.odin
new file mode 100644
index 0000000..bc7e4d3
--- /dev/null
+++ b/gui/src/data.odin
@@ -0,0 +1,35 @@
+package main
+
+Catalog :: struct {
+	name:         string,
+	release:      string,
+	description:  ^string,
+	object_count: ^u64,
+}
+
+CatalogObject :: struct {
+	id:          string,
+	catalog:     string,
+	object_type: string,
+	ra:          f64,
+	dec:         f64,
+	redshift:    f64,
+}
+
+APIError :: struct {
+	code:    int,
+	message: string,
+}
+
+get_catalogs :: proc() -> ([dynamic]Catalog, ^APIError) {
+	return nil, nil
+}
+
+get_catalog :: proc(name: string) -> (^Catalog, ^APIError) {
+	return nil, nil
+}
+
+get_catalog_objects :: proc(catalog_name: string) -> ([dynamic]CatalogObject, ^APIError) {
+	return nil, nil
+}
+