diff --git a/src/lib/snapshot/diff.py b/src/lib/snapshot/diff.py
new file mode 100644
index 0000000..9832068
--- /dev/null
+++ b/src/lib/snapshot/diff.py
@@ -0,0 +1,53 @@
+import os 
+
+def recursive_raw_diff(tree_a, tree_b, tree_a_tag, tree_b_tag, path, res):
+  a_keys_not_in_b = set(tree_a.keys()) - set(tree_b.keys())
+  # b_keys_not_in_a = set(tree_b.keys()) - set(tree_a.keys())
+  ## name last is a dir
+  if a_keys_not_in_b:
+    for key in a_keys_not_in_b:
+      print(f'node {path}{key} subtree added in {tree_a_tag}')
+      res[f'{path}{key}'] = {
+        tree_a_tag : 'x',
+      }
+
+  for key_a, hsh_a in tree_a.items():
+    hsh_b = tree_b.get(key_a)
+
+    if hsh_b is None:
+      '''
+       already in `a_keys_not_in_b`
+      '''
+      continue
+
+
+
+    if isinstance(hsh_a, str):
+      if hsh_a == hsh_b: continue
+
+      res[f'{path}{key_a}'] = {
+        tree_a_tag : 'x',
+        tree_b_tag : 'x',
+      }
+
+      res[f'{path}{key_a}']['%s_hash' %(tree_a_tag,)] = hsh_a
+      res[f'{path}{key_a}']['%s_hash' %(tree_b_tag,)] = hsh_b
+      continue
+
+
+    recursive_raw_diff(hsh_a, hsh_b,tree_a_tag, tree_b_tag, '%s%s/' % (path, key_a,), res)
+
+def raw_diff(tree_a, tree_b, tree_a_tag='tree_a', tree_b_tag='tree_b', path='./'):
+  '''
+    it returns a dict where the key is the relative path of node givin these informations
+
+      - node present in tree_a     
+      - node present in tree_b
+      - hash is the same or differ
+  '''
+  res = {}
+  if not path.endswith(os.sep): path = path + os.sep
+  recursive_raw_diff(tree_a, tree_b, tree_a_tag=tree_a_tag, tree_b_tag=tree_b_tag, path=path, res=res)
+  ## note the tree inversion
+  recursive_raw_diff(tree_b, tree_a, tree_a_tag=tree_b_tag, tree_b_tag=tree_a_tag, path=path, res=res)
+  return res
diff --git a/src/testing/rawdiff.py b/src/testing/rawdiff.py
new file mode 100644
index 0000000..65db63b
--- /dev/null
+++ b/src/testing/rawdiff.py
@@ -0,0 +1,12 @@
+from lib.snapshot import diff
+
+
+
+tree_a = {'taglioCapelli4.jpg': '5af62402ec7716e8d729b0683061f0c4', 'taglioCapelli5.jpg': '9c42961af589a279c4c828925291153b', 'pino.txt': 'd41d8cd98f00b204e9800998ecf8427e', 'taglioCapelli6.jpg': '4059905eab817c33ee48f912af80fdb7', 'spartiti_sepu': {'amber.py': 'a6ef147511264ecdc7d6061979892c44', 'bo.txt': 'd7aa6cbc6aa0ace3225ee1738b2d5c6b',  'ciao': {'amber.py': 'a6ef147511264ecdc7d6061979892c44', 'bo.txt': 'd7aa6cbc6aa0ace3225ee1738b2d5c6b'},'added_folder': {}}, 'preferiti.txt': 'af45981ef2be534dbb37f96833d3fd04'}
+
+tree_b = {'taglioCapelli4.jpg': '5af62402ec7716e8d729b0683061f0c4', 'taglioCapelli5.jpg': '9c42961af589a279c4c828925291153b', 'pino.txt': 'd41d8cd98f00b204e9800998ecf8427e', 'taglioCapelli6.jpg': '4059905eab817c33ee48f912af80fdb7', 'spartiti_sepu': {'amber.py': 'a6ef147511264ecdc7d6061979892c44', 'bo.txt': 'd7aa6cbc6aa0ace3225ee1738b2d5c6b', 'added_folder': {'preferiti.txt' : 'af45981ef2be534dbb37f96833d3fd03'}}, 'preferiti.txt': 'af45981ef2be534dbb37f9fffffffff'}
+
+
+
+def test_raw_diff():
+  return diff.raw_diff(tree_a, tree_b)