diff --git a/chainlib/chain.py b/chainlib/chain.py
new file mode 100644
index 0000000..2cdbc64
--- /dev/null
+++ b/chainlib/chain.py
@@ -0,0 +1,42 @@
+class ChainSpec:
+
+    def __init__(self, engine, common_name, network_id, tag=None):
+        self.o = {
+                'engine': engine,
+                'common_name': common_name,
+                'network_id': network_id,
+                'tag': tag,
+                }
+
+    def network_id(self):
+        return self.o['network_id']
+
+
+    def chain_id(self):
+        return self.o['network_id']
+
+
+    def engine(self):
+        return self.o['engine']
+
+
+    def common_name(self):
+        return self.o['common_name']
+
+
+    @staticmethod
+    def from_chain_str(chain_str):
+        o = chain_str.split(':')
+        if len(o) < 3:
+            raise ValueError('Chain string must have three sections, got {}'.format(len(o)))
+        tag = None
+        if len(o) == 4:
+            tag = o[3]
+        return ChainSpec(o[0], o[1], int(o[2]), tag)
+
+
+    def __str__(self):
+        s = '{}:{}:{}'.format(self.o['engine'], self.o['common_name'], self.o['network_id'])
+        if self.o['tag'] != None:
+            s += ':' + self.o['tag']
+        return s
diff --git a/tests/base.py b/tests/base.py
new file mode 100644
index 0000000..e8e3a04
--- /dev/null
+++ b/tests/base.py
@@ -0,0 +1,12 @@
+import unittest
+
+
+class TestBase(unittest.TestCase):
+
+
+    def setUp(self):
+        pass
+
+
+    def tearDown(self):
+        pass
diff --git a/tests/test_chain.py b/tests/test_chain.py
new file mode 100644
index 0000000..1c2bc95
--- /dev/null
+++ b/tests/test_chain.py
@@ -0,0 +1,22 @@
+import unittest
+
+from chainlib.chain import ChainSpec
+
+from tests.base import TestBase
+
+
+class TestChain(TestBase):
+
+    def test_chain_spec(self):
+
+        s = ChainSpec.from_chain_str('foo:bar:3')
+        s = ChainSpec.from_chain_str('foo:bar:3:baz')
+
+        with self.assertRaises(ValueError):
+            s = ChainSpec.from_chain_str('foo:bar:a')
+            s = ChainSpec.from_chain_str('foo:bar')
+            s = ChainSpec.from_chain_str('foo')
+
+
+if __name__ == '__main__':
+    unittest.main()