diff --git a/.gitignore b/.gitignore
@@ -161,7 +161,7 @@ cython_debug/
 #  be found at https://github.com/github/gitignore/blob/main/Global/JetBrains.gitignore
 #  and can be added to the global gitignore or merged into this file.  For a more nuclear
 #  option (not recommended) you can uncomment the following to ignore the entire idea folder.
-#.idea/
+.idea/
 
 # VSCode
 .vscode/

diff --git a/package/export/__main__.py b/package/export/__main__.py
@@ -66,7 +66,8 @@ def _gen_rst_docs(source: Path, refs_path: Path, only_web: bool = False, only_ma
     with open(source / "docs/index.rst", "wt") as idx_f:
         idx_f.write(
             convert_file(source_file=source / "docs/index.md", format="md", to="rst").replace(
-                "\r\n", "\n"  # remove carriage return in windows
+                "\r\n",
+                "\n",  # remove carriage return in windows
             )
             + "\n\n.. toctree::"
             + "\n   :hidden:"

diff --git a/src/__init__.py b/src/__init__.py
@@ -0,0 +1 @@
+"""Validators."""
diff --git a/src/validators/domain.py b/src/validators/domain.py
@@ -80,7 +80,6 @@ def domain(
         return False
 
     try:
-
         service_record = r"_" if rfc_2782 else ""
         trailing_dot = r"\.?$" if rfc_1034 else r"$"
 

diff --git a/src/validators/i18n/__init__.py b/src/validators/i18n/__init__.py
@@ -5,6 +5,7 @@
 from .fi import fi_business_id, fi_ssn
 from .fr import fr_department, fr_ssn
 from .ind import ind_aadhar, ind_pan
+from .ru import ru_inn
 
 __all__ = (
     "fi_business_id",
@@ -17,4 +18,5 @@
     "fr_ssn",
     "ind_aadhar",
     "ind_pan",
+    "ru_inn",
 )
diff --git a/src/validators/i18n/fi.py b/src/validators/i18n/fi.py
@@ -24,9 +24,7 @@ def _ssn_pattern(ssn_check_marks: str):
         (\d{{2}}))
         [ABCDEFYXWVU+-]
         (?P<serial>(\d{{3}}))
-        (?P<checksum>[{check_marks}])$""".format(
-            check_marks=ssn_check_marks
-        ),
+        (?P<checksum>[{check_marks}])$""".format(check_marks=ssn_check_marks),
         re.VERBOSE,
     )
 

diff --git a/src/validators/i18n/ru.py b/src/validators/i18n/ru.py
@@ -0,0 +1,64 @@
+"""Russia INN."""
+
+from validators.utils import validator
+
+
+@validator
+def ru_inn(value: str):
+    """Validate a Russian INN (Taxpayer Identification Number).
+
+    The INN can be either 10 digits (for companies) or 12 digits (for individuals).
+    The function checks both the length and the control digits according to Russian tax rules.
+
+    Examples:
+        >>> ru_inn('500100732259')  # Valid 12-digit INN
+        True
+        >>> ru_inn('7830002293')    # Valid 10-digit INN
+        True
+        >>> ru_inn('1234567890')    # Invalid INN
+        ValidationFailure(func=ru_inn, args={'value': '1234567890'})
+
+    Args:
+        value: Russian INN string to validate. Can contain only digits.
+
+    Returns:
+        (Literal[True]): If `value` is a valid Russian INN.
+        (ValidationError): If `value` is an invalid Russian INN.
+
+    Note:
+        The validation follows the official algorithm:
+        - For 10-digit INN: checks 10th control digit
+        - For 12-digit INN: checks both 11th and 12th control digits
+    """
+    if not value:
+        return False
+
+    try:
+        digits = list(map(int, value))
+        # company
+        if len(digits) == 10:
+            weight_coefs = [2, 4, 10, 3, 5, 9, 4, 6, 8, 0]
+            control_number = sum([d * w for d, w in zip(digits, weight_coefs)]) % 11
+            return (
+                (control_number % 10) == digits[-1]
+                if control_number > 9
+                else control_number == digits[-1]
+            )
+        # person
+        elif len(digits) == 12:
+            weight_coefs1 = [7, 2, 4, 10, 3, 5, 9, 4, 6, 8, 0, 0]
+            control_number1 = sum([d * w for d, w in zip(digits, weight_coefs1)]) % 11
+            weight_coefs2 = [3, 7, 2, 4, 10, 3, 5, 9, 4, 6, 8, 0]
+            control_number2 = sum([d * w for d, w in zip(digits, weight_coefs2)]) % 11
+            print(control_number1, control_number2, value)
+            return (
+                (control_number1 % 10) == digits[-2]
+                if control_number1 > 9
+                else control_number1 == digits[-2] and (control_number2 % 10) == digits[-1]
+                if control_number2 > 9
+                else control_number2 == digits[-1]
+            )
+        else:
+            return False
+    except ValueError:
+        return False
diff --git a/src/validators/uri.py b/src/validators/uri.py
@@ -47,10 +47,20 @@ def uri(value: str, /):
     # url
     if any(
         # fmt: off
-        value.startswith(item) for item in {
-            "ftp", "ftps", "git", "http", "https",
-            "irc", "rtmp", "rtmps", "rtsp", "sftp",
-            "ssh", "telnet",
+        value.startswith(item)
+        for item in {
+            "ftp",
+            "ftps",
+            "git",
+            "http",
+            "https",
+            "irc",
+            "rtmp",
+            "rtmps",
+            "rtsp",
+            "sftp",
+            "ssh",
+            "telnet",
         }
         # fmt: on
     ):

diff --git a/src/validators/url.py b/src/validators/url.py
@@ -46,9 +46,18 @@ def _validate_scheme(value: str):
         value
         # fmt: off
         in {
-            "ftp", "ftps", "git", "http", "https",
-            "irc", "rtmp", "rtmps", "rtsp", "sftp",
-            "ssh", "telnet",
+            "ftp",
+            "ftps",
+            "git",
+            "http",
+            "https",
+            "irc",
+            "rtmp",
+            "rtmps",
+            "rtsp",
+            "sftp",
+            "ssh",
+            "telnet",
         }
         # fmt: on
         if value

diff --git a/tests/i18n/test_ru.py b/tests/i18n/test_ru.py
@@ -0,0 +1,48 @@
+"""Test i18n/inn."""
+
+# external
+import pytest
+
+# local
+from validators import ValidationError
+from validators.i18n.ru import ru_inn
+
+
+@pytest.mark.parametrize(
+    ("value",),
+    [
+        ("2222058686",),
+        ("7709439560",),
+        ("5003052454",),
+        ("7730257499",),
+        ("3664016814",),
+        ("026504247480",),
+        ("780103209220",),
+        ("7707012148",),
+        ("140700989885",),
+        ("774334078053",),
+    ],
+)
+def test_returns_true_on_valid_ru_inn(value: str):
+    """Test returns true on valid russian individual tax number."""
+    assert ru_inn(value)
+
+
+@pytest.mark.parametrize(
+    ("value",),
+    [
+        ("2222058687",),
+        ("7709439561",),
+        ("5003052453",),
+        ("7730257490",),
+        ("3664016815",),
+        ("026504247481",),
+        ("780103209222",),
+        ("7707012149",),
+        ("140700989886",),
+        ("774334078054",),
+    ],
+)
+def test_returns_false_on_valid_ru_inn(value: str):
+    """Test returns true on valid russian individual tax number."""
+    assert isinstance(ru_inn(value), ValidationError)
diff --git a/tests/test_url.py b/tests/test_url.py
@@ -156,7 +156,7 @@ def test_returns_true_on_valid_private_url(value: str, private: Optional[bool]):
         ":// should fail",
         "http://foo.bar/foo(bar)baz quux",
         "http://-error-.invalid/",
-        "http://www.\uFFFD.ch",
+        "http://www.\ufffd.ch",
         "http://-a.b.co",
         "http://a.b-.co",
         "http://1.1.1.1.1",
-Original file line number
+Diff line change
@@ Expand Up / @@ -80,7 +80,6 @@ def domain( @@
             return False
         try:
             service_record = r"_" if rfc_2782 else ""
             trailing_dot = r"\.?$" if rfc_1034 else r"$"
@@ Expand Down @@