Cereal works pretty well so I may use it, but there's one more library I want to try first called tser.

tests/config.cpp

@@ -4,6 +4,7 @@
 #include "config.hpp"
 #include <any>
 #include "dinkyecs.hpp"
+#include "components.hpp"
 
 using namespace fmt;
 using std::string;
@@ -60,3 +61,46 @@ TEST_CASE("can go into a world", "[config]") {
   Config &cfg = world.get_the<Config>();
   REQUIRE(cfg["types"]["NUMBER"] == 1234);
 }
+
+#include <cereal/types/unordered_map.hpp>
+#include <cereal/types/memory.hpp>
+#include <cereal/archives/json.hpp>
+#include <cereal/archives/binary.hpp>
+#include <cereal/archives/portable_binary.hpp>
+#include <fstream>
+
+struct MyData
+{
+  int x, y, z;
+  std::string tiles;
+
+  template<class Archive>
+    serialize(Archive &ar) { ar(x, y, z, tiles); }
+};
+
+
+TEST_CASE("test using serialization", "[config]") {
+  {
+    std::ofstream os("cereal.json", std::ios::binary);
+    cereal::JSONOutputArchive oarchive(os);
+
+    MyData m1{1,2,3, "\u2849█Ω♣"};
+    MyData m2{5,6,7, "\u2849█Ω♣"};
+    MyData m3{8,9,10, "\u2849█Ω♣"};
+
+    oarchive(m1, m2, m3);
+  }
+
+  {
+    std::ifstream is("cereal.json", std::ios::binary);
+    cereal::JSONInputArchive iarchive(is);
+
+    MyData m1, m2, m3;
+
+    iarchive(m1, m2, m3);
+
+    REQUIRE(m1.tiles == "\u2849█Ω♣");
+    REQUIRE(m2.tiles == "\u2849█Ω♣");
+    REQUIRE(m3.tiles == "\u2849█Ω♣");
+  }
+}