diff --git a/src/common/db2.h b/src/common/db2.h
index f4598da..c56172d 100644
--- a/src/common/db2.h
+++ b/src/common/db2.h
@@ -19,10 +19,41 @@
 #include "common.h"
 #include "mmap.h"
 
+#include <nlohmann/json.hpp>
+#include <primitives/templates2/overload.h>
 #include <primitives/templates2/type_name.h>
 
 #include <variant>
 
+std::string utf8_to_dbstr(const char8_t *s, int codepage = 1251) {
+    return str2str((const char *)s, CP_UTF8, codepage);
+}
+std::string utf8_to_dbstr(const char *s) {
+    return utf8_to_dbstr((const char8_t *)s);
+}
+std::string utf8_to_dbstr(const std::string &s) {
+    return utf8_to_dbstr((const char8_t *)s.c_str());
+}
+
+struct mem_stream {
+    std::vector<uint8_t> d;
+
+    template <typename T>
+    operator T &() {
+        d.resize(d.size() + sizeof(T));
+        auto p = d.data() + d.size() - sizeof(T);
+        auto &r = *(T *)p;
+        return r;
+    }
+    void operator+=(const mem_stream &s) {
+        d.append_range(s.d);
+    }
+    template <typename T>
+    T &at(size_t i) {
+        return *(T *)(d.data() + i);
+    }
+};
+
 struct db2 {
     using char20 = char[0x20];
 
@@ -127,10 +158,124 @@ struct db2 {
 
             db2_memory m;
 
+            auto begin(this auto &&d) {return d.m.begin();}
+            auto end(this auto &&d) {return d.m.end();}
             auto &operator[](this auto &&d, const std::string &s) {
                 return d.m[s];
             }
-            void save() {
+            auto to_json() const {
+                nlohmann::json ja;
+                for (auto &&[tn,t] : m) {
+                    auto &jt = ja[tn];
+                    for (auto &&[vn,v] : t) {
+                        auto &jv = jt[vn];
+                        for (auto &&[fn, fv] : v) {
+                            std::visit(overload{
+                                [&](const int &v){jv[fn] = v;},
+                                [&](const float &v){jv[fn] = v;},
+                                [&](const std::string &v){jv[fn] = v;},
+                                }, fv);
+                        }
+                    }
+                }
+                return ja;
+            }
+            size_t fields_size() const {
+                size_t sz{};
+                return sz;
+            }
+            size_t tables_size() const {
+                size_t sz{};
+                return sz;
+            }
+            size_t tab_size() const {
+                return tables_size() + fields_size();
+            }
+            size_t ind_size() const {
+                return tables_size() + fields_size();
+            }
+            size_t dat_size() const {
+                return tables_size() + fields_size();
+            }
+            void save(const path &fn) {
+                auto tabsz = tab_size();
+                auto indsz = ind_size();
+                auto datsz = dat_size();
+
+                auto s_to_char20 = [&](char20 &dst, const std::string &in) {
+                    auto s = utf8_to_dbstr(in);
+                    if (s.size() + 1 > sizeof(char20)) {
+                        throw std::runtime_error{"too long string"};
+                    }
+                    memcpy(dst, s.c_str(), s.size());
+                };
+
+                mem_stream tabv,tabv_fields;
+                tab &tab_ = tabv;
+                auto get_tab = [&](){};
+                int table_id{1};
+                int total_fields{};
+                for (auto &&[tn,td] : m) {
+                    tab::table &t = tabv;
+                    t.id = table_id;
+                    s_to_char20(t.name, tn);
+
+                    std::set<std::pair<std::string, field_type>> fields;
+                    for (auto &&[_,fd] : td) {
+                        for (auto &&[fn,fv] : fd) {
+                            fields.emplace(std::pair<std::string, field_type>{fn,(field_type)fv.index()});
+                        }
+                    }
+                    int field_id{1};
+                    for (auto &&[fn,ft] : fields) {
+                        tab::field &f = tabv_fields;
+                        f.id = field_id;
+                        f.table_id = table_id;
+                        f.type = ft;
+                        s_to_char20(f.name, fn);
+                        ++total_fields;
+                    }
+
+                    ++table_id;
+                }
+                tabv += tabv_fields;
+                {
+                    auto &tab_ = tabv.at<tab>(0);
+                    tab_.n_tables = m.size();
+                    tab_.n_fields = total_fields;
+                }
+
+                mem_stream indv, datv;
+                for (auto &&[tn, td] : m) {
+                    tab::table &t = tabv;
+                    t.id = table_id;
+                    s_to_char20(t.name, tn);
+
+                    std::set<std::pair<std::string, field_type>> fields;
+                    for (auto &&[_, fd] : td) {
+                    }
+                }
+
+
+                /*db2 x{};
+                auto newdb = x.open();
+                for (auto &&[t,vals] : ja.items()) {
+                    for (auto &&[v,fields] : vals.items()) {
+                        for (auto &&[f,val] : fields.items()) {
+                            auto s = newdb(t, v, f);
+                            if (0) {
+                            } else if (val.is_number_float()) {
+                                s = val.get<float>();
+                            } else if (val.is_number_integer()) {
+                                s = val.get<int>();
+                            } else if (val.is_string()) {
+                                s = val.get<std::string>();
+                            } else {
+                                throw std::logic_error{"bad type"};
+                            }
+                        }
+                    }
+                }*/
 
             }
         };
@@ -183,68 +328,9 @@ struct db2 {
             }
             return m;
         }
-        /*auto to_json() const {
-            auto prepare_string = [](auto &&in) {
-                auto s = str2utf8(in);
-                boost::trim(s);
-                return s;
-            };
-
-            auto tbl = tab_.data->tables();
-            nlohmann::json ja;
-            for (auto &&t : tbl) {
-                auto &jt = ja[prepare_string(t.name)];
-                auto fields = tab_.data->fields(t.id);
-                for (auto &&v : ind_.data->values(t.id)) {
-                    auto vn = prepare_string(v.name);
-                    if (jt.contains(vn)) {
-                        throw std::logic_error{"duplicate"};
-                    }
-                    auto &jv = jt[vn];
-                    auto p = dat_.f.p + v.offset;
-                    auto max = p + v.size;
-                    while (p < max) {
-                        auto vb = (db2::dat::field_value_base *)p;
-                        p += sizeof(db2::dat::field_value_base);
-                        auto f = std::ranges::find_if(fields, [&](auto &f) {
-                            return f.id == vb->field_id;
-                        });
-                        if (f == fields.end()) {
-                            throw std::logic_error{"unknown field"};
-                        }
-                        auto fn = prepare_string(f->name);
-                        switch (f->type) {
-                        case db2::field_type::integer:
-                            jv[fn] = *(int *)p;
-                            break;
-                        case db2::field_type::float_:
-                            jv[fn] = *(float *)p;
-                            break;
-                        case db2::field_type::string:
-                            jv[fn] = prepare_string((const char *)p);
-                            break;
-                        default:
-                            throw std::logic_error{"bad type"};
-                        }
-                        p += vb->size;
-                    }
-                }
-            }
-        }*/
     };
 
     auto open() {
         return files{*this, fn};
     }
-
-private:
-    std::string utf8_to_dbstr(const std::string &s) const {
-        return utf8_to_dbstr((const char8_t *)s.c_str());
-    }
-    std::string utf8_to_dbstr(const char *s) const {
-        return utf8_to_dbstr((const char8_t *)s);
-    }
-    std::string utf8_to_dbstr(const char8_t *s) const {
-        return str2str((const char *)s, CP_UTF8, codepage);
-    }
 };
diff --git a/src/db_extractor2/db_extractor2.cpp b/src/db_extractor2/db_extractor2.cpp
index 3d4df53..6a84bf7 100644
--- a/src/db_extractor2/db_extractor2.cpp
+++ b/src/db_extractor2/db_extractor2.cpp
@@ -24,8 +24,6 @@
 #include <primitives/sw/main.h>
 #include <primitives/sw/settings.h>
 #include <primitives/sw/cl.h>
-#include <primitives/templates2/overload.h>
-#include <nlohmann/json.hpp>
 
 #include <fstream>
 #include <span>
@@ -39,43 +37,9 @@ int main(int argc, char *argv[])
 
     db2 db{db_fn};
     auto f = db.open();
-    auto tbl = f.to_map();
-
-    nlohmann::json ja;
-    for (auto &&[tn,t] : tbl) {
-        auto &jt = ja[tn];
-        for (auto &&[vn,v] : t) {
-            auto &jv = jt[vn];
-            for (auto &&[fn, fv] : v) {
-                std::visit(overload{
-                    [&](const int &v){jv[fn] = v;},
-                    [&](const float &v){jv[fn] = v;},
-                    [&](const std::string &v){jv[fn] = v;},
-                    }, fv);
-            }
-        }
-    }
-    write_file(path{db_fn} += ".json", ja.dump(1));
-
-    db2 x{path{db_fn} += "new"};
-    auto newdb = x.open();
-    for (auto &&[t,vals] : ja.items()) {
-        for (auto &&[v,fields] : vals.items()) {
-            for (auto &&[f,val] : fields.items()) {
-                auto s = newdb(t, v, f);
-                if (0) {
-                } else if (val.is_number_float()) {
-                    s = val.get<float>();
-                } else if (val.is_number_integer()) {
-                    s = val.get<int>();
-                } else if (val.is_string()) {
-                    s = val.get<std::string>();
-                } else {
-                    throw std::logic_error{"bad type"};
-                }
-            }
-        }
-    }
+    auto m = f.to_map();
+    write_file(path{db_fn} += ".json", m.to_json().dump(1));
+    m.save(path{db_fn} += "new");
 
     return 0;
 }
diff --git a/sw.cpp b/sw.cpp
index a7fc3e9..d6fb5fa 100644
--- a/sw.cpp
+++ b/sw.cpp
@@ -96,6 +96,7 @@ void build(Solution &s)
 
     auto &aim1_mod_maker = add_exe_with_common("aim1.mod_maker", "aim1_mod_maker"); // actually a library
     aim1_mod_maker.Public += "pub.egorpugin.primitives.command"_dep;
+    aim1_mod_maker.Public += "org.sw.demo.nlohmann.json.natvis"_dep;
 
     auto &aim1_community_fix = tools.addExecutable("examples.mods.aim1.community_fix");
     {