diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 445c21f..8aa8066 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -36,18 +36,23 @@ Now you're ready to make changes to `src/fsrs` and see your changes reflected im
 
 This project follows [semantic versioning](https://semver.org/), so please make sure to increment the version number in [pyproject.toml](pyproject.toml) when contributing new code.
 
-### Format and test
+### Lint, format and test
 
-Py-FSRS follows the [black](https://github.com/psf/black) code formatting style and uses [pytest](https://docs.pytest.org) to run its tests. In order for your contribution to be accepted, your code must be properly formatted and be able to pass the tests.
+Py-FSRS uses [Ruff](https://github.com/astral-sh/ruff) for linting and formatting and uses [pytest](https://docs.pytest.org) to run its tests. In order for your contribution to be accepted, your code must pass linting/formatting checks and be able to pass the tests.
 
 You can install these packages with
 ```
-pip install black pytest
+pip install ruff pytest
+```
+
+Lint your code with:
+```
+ruff check --fix
 ```
 
 Format your code with:
 ```
-black .
+ruff format
 ```
 
 Run the tests with:
diff --git a/README.md b/README.md
index 6d1c230..3d86439 100644
--- a/README.md
+++ b/README.md
@@ -13,7 +13,7 @@
 <div align="center" style="text-decoration: none;">
     <a href="https://pypi.org/project/fsrs/"><img src="https://img.shields.io/pypi/v/fsrs"></a>
     <a href="https://github.com/open-spaced-repetition/py-fsrs/blob/main/LICENSE" style="text-decoration: none;"><img src="https://img.shields.io/badge/License-MIT-brightgreen.svg"></a>
-    <a href="https://github.com/psf/black" style="text-decoration: none;"><img src="https://img.shields.io/badge/code%20style-black-000000.svg"></a>
+    <a href="https://github.com/astral-sh/ruff"><img src="https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/astral-sh/ruff/main/assets/badge/v2.json"></a>
 </div>
 <br />
 
@@ -177,8 +177,4 @@ Rating.Easy # recall; perfect response
 
 ## Contribute
 
-Checkout [CONTRIBUTING](CONTRIBUTING.md) to help improve Py-FSRS!
-
-## License
-
-Distributed under the MIT License. See [LICENSE](LICENSE) for more information.
+Checkout [CONTRIBUTING](CONTRIBUTING.md) to help improve Py-FSRS!
\ No newline at end of file
diff --git a/src/fsrs/fsrs.py b/src/fsrs/fsrs.py
index 0d211c7..2259060 100644
--- a/src/fsrs/fsrs.py
+++ b/src/fsrs/fsrs.py
@@ -22,7 +22,6 @@ def __init__(
     def review_card(
         self, card: Card, rating: Rating, now: Optional[datetime] = None
     ) -> tuple[Card, ReviewLog]:
-
         scheduling_cards = self.repeat(card, now)
 
         card = scheduling_cards[rating].card
@@ -30,8 +29,9 @@ def review_card(
 
         return card, review_log
 
-    def repeat(self, card: Card, now: Optional[datetime] = None) -> dict[int, SchedulingInfo]:
-
+    def repeat(
+        self, card: Card, now: Optional[datetime] = None
+    ) -> dict[int, SchedulingInfo]:
         if now is None:
             now = datetime.now(timezone.utc)
 
diff --git a/tests/test_fsrs.py b/tests/test_fsrs.py
index 7ea270b..23134c9 100644
--- a/tests/test_fsrs.py
+++ b/tests/test_fsrs.py
@@ -17,7 +17,6 @@ def print_scheduling_cards(scheduling_cards):
 
 
 class TestPyFSRS:
-
     def test_repeat(self):
         f = FSRS()
         f.p.w = (
@@ -73,7 +72,6 @@ def test_repeat(self):
         assert ivl_history == [0, 5, 16, 43, 106, 236, 0, 0, 12, 25, 47, 85, 147]
 
     def test_repeat_default_arg(self):
-
         f = FSRS()
 
         card_object = Card()
@@ -92,7 +90,6 @@ def test_repeat_default_arg(self):
         assert time_delta.seconds > 500  # due in approx. 8-10 minutes
 
     def test_datetime(self):
-
         f = FSRS()
         card = Card()
 
@@ -118,7 +115,6 @@ def test_datetime(self):
         assert card.due >= card.last_review
 
     def test_Card_serialize(self):
-
         f = FSRS()
 
         # create card object the normal way
@@ -158,7 +154,6 @@ def test_Card_serialize(self):
         assert card.to_dict() != repeated_card.to_dict()
 
     def test_ReviewLog_serialize(self):
-
         f = FSRS()
 
         card = Card()
@@ -204,7 +199,6 @@ def test_ReviewLog_serialize(self):
         assert review_log.to_dict() != next_review_log.to_dict()
 
     def test_review_card(self):
-
         f = FSRS()
         f.p.w = (
             1.14,
@@ -260,7 +254,6 @@ def test_review_card(self):
         assert ivl_history == [0, 5, 16, 43, 106, 236, 0, 0, 12, 25, 47, 85, 147]
 
     def test_custom_scheduler_args(self):
-
         f = FSRS(
             w=(
                 1.14,