diff --git a/src/dopt_pollublock_blockchain/types.py b/src/dopt_pollublock_blockchain/types.py
new file mode 100644
index 0000000..1633b2c
--- /dev/null
+++ b/src/dopt_pollublock_blockchain/types.py
@@ -0,0 +1,12 @@
+from typing import TypeAlias, TypedDict
+
+BlockIndex: TypeAlias = int
+
+
+class SerializedPyBlock(TypedDict):
+    index: int
+    timestamp: int
+    nonce: int
+    previous_hash: str
+    hash: str
+    data: str