diff --git a/lcm/dbmemory.py b/lcm/dbmemory.py
new file mode 100644
index 0000000..75d1f88
--- /dev/null
+++ b/lcm/dbmemory.py
@@ -0,0 +1,116 @@
+from dbbase import DbException, dbbase
+from http import HTTPStatus
+from uuid import uuid4
+from copy import deepcopy
+
+
+class dbmemory(dbbase):
+
+    def __init__(self):
+        self.db = {}
+
+    @staticmethod
+    def _format_filter(filter):
+        return filter    # TODO
+
+    def _find(self, table, filter):
+        for i, row in enumerate(self.db.get(table, ())):
+            match = True
+            if filter:
+                for k, v in filter.items():
+                    if k not in row or v != row[k]:
+                        match = False
+            if match:
+                yield i, row
+
+    def get_list(self, table, filter={}):
+        try:
+            l = []
+            for _, row in self._find(table, self._format_filter(filter)):
+                l.append(deepcopy(row))
+            return l
+        except DbException:
+            raise
+        except Exception as e:  # TODO refine
+            raise DbException(str(e))
+
+    def get_one(self, table, filter={}, fail_on_empty=True, fail_on_more=True):
+        try:
+            l = None
+            for _, row in self._find(table, self._format_filter(filter)):
+                if not fail_on_more:
+                    return deepcopy(row)
+                if l:
+                    raise DbException("Found more than one entry with filter='{}'".format(filter),
+                                      HTTPStatus.CONFLICT.value)
+                l = row
+            if not l and fail_on_empty:
+                raise DbException("Not found entry with filter='{}'".format(filter), HTTPStatus.NOT_FOUND.value)
+            return deepcopy(l)
+        except Exception as e:  # TODO refine
+            raise DbException(str(e))
+
+    def del_list(self, table, filter={}):
+        try:
+            id_list = []
+            for i, _ in self._find(table, self._format_filter(filter)):
+                id_list.append(i)
+            deleted = len(id_list)
+            for i in id_list:
+                del self.db[table][i]
+            return {"deleted": deleted}
+        except DbException:
+            raise
+        except Exception as e:  # TODO refine
+            raise DbException(str(e))
+
+    def del_one(self, table, filter={}, fail_on_empty=True):
+        try:
+            for i, _ in self._find(table, self._format_filter(filter)):
+                break
+            else:
+                if fail_on_empty:
+                    raise DbException("Not found entry with filter='{}'".format(filter), HTTPStatus.NOT_FOUND.value)
+                return None
+            del self.db[table][i]
+            return {"deleted": 1}
+        except Exception as e:  # TODO refine
+            raise DbException(str(e))
+
+    def replace(self, table, filter, indata, fail_on_empty=True):
+        try:
+            for i, _ in self._find(table, self._format_filter(filter)):
+                break
+            else:
+                if fail_on_empty:
+                    raise DbException("Not found entry with filter='{}'".format(filter), HTTPStatus.NOT_FOUND.value)
+                return None
+            self.db[table][i] = deepcopy(indata)
+            return {"upadted": 1}
+        except Exception as e:  # TODO refine
+            raise DbException(str(e))
+
+    def create(self, table, indata):
+        try:
+            id = indata.get("_id")
+            if not id:
+                id = str(uuid4())
+                indata["_id"] = id
+            if table not in self.db:
+                self.db[table] = []
+            self.db[table].append(deepcopy(indata))
+            return id
+        except Exception as e:  # TODO refine
+            raise DbException(str(e))
+
+
+if __name__ == '__main__':
+    # some test code
+    db = dbmemory()
+    db.create("test", {"_id": 1, "data": 1})
+    db.create("test", {"_id": 2, "data": 2})
+    db.create("test", {"_id": 3, "data": 3})
+    print("must be 3 items:", db.get_list("test"))
+    print("must return item 2:", db.get_list("test", {"_id": 2}))
+    db.del_one("test", {"_id": 2})
+    print("must be emtpy:", db.get_list("test", {"_id": 2}))