diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
new file mode 100644
index 0000000..c13a320
--- /dev/null
+++ b/.pre-commit-config.yaml
@@ -0,0 +1,15 @@
+# Pre-commit hooks configuration
+# See https://pre-commit.com for more information
+repos:
+  - repo: https://github.com/psf/black
+    rev: 24.10.0
+    hooks:
+      - id: black
+        language_version: python3
+        args: ['--line-length=119']
+
+  - repo: https://github.com/igorshubovych/markdownlint-cli
+    rev: v0.43.0
+    hooks:
+      - id: markdownlint
+        args: ['--config', '.markdownlint.json']
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 5485daf..738152d 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -26,7 +26,16 @@ contributors.
    pip install -e ".[dev]"
    ```
 
-4. Create a branch for your changes:
+4. Install pre-commit hooks:
+
+   ```bash
+   pre-commit install
+   ```
+
+   This will automatically run black (Python formatter with line-length=119) and markdownlint
+   before each commit.
+
+5. Create a branch for your changes:
 
    ```bash
    git checkout -b feature/your-feature-name
@@ -50,18 +59,30 @@ pytest --cov=bad_path --cov-report=term-missing
 
 ### Code Quality
 
+Format code with black (line-length=119):
+
+```bash
+black .
+```
+
 Check code with ruff:
 
 ```bash
 ruff check .
 ```
 
-Format code (if needed):
+Format code with ruff (if needed):
 
 ```bash
 ruff format .
 ```
 
+Run pre-commit hooks manually on all files:
+
+```bash
+pre-commit run --all-files
+```
+
 ### Building Documentation
 
 Build the documentation locally:
@@ -79,8 +100,9 @@ The built documentation will be in `docs/_build/html/`.
 
 - Follow PEP 8 style guide
 - Use Python 3.10+ features (type unions with |, match/case statements)
-- Line length: 100 characters (configured in pyproject.toml)
-- Use ruff for linting and formatting
+- Line length: 119 characters for black formatting, 100 characters for ruff
+- Use black for automatic code formatting
+- Use ruff for linting and additional formatting
 
 ### Docstrings
 
@@ -116,6 +138,7 @@ The built documentation will be in `docs/_build/html/`.
 3. **Test Your Changes**:
    - Run the full test suite
    - Check code quality with ruff
+   - Format code with black (or run pre-commit hooks)
    - Build documentation to check for errors
    - Test on multiple platforms if possible
 
diff --git a/bad_path/checker.py b/bad_path/checker.py
index a133366..296fd50 100644
--- a/bad_path/checker.py
+++ b/bad_path/checker.py
@@ -353,9 +353,7 @@ def __init__(
                 self._user_paths_ok = user_paths_ok
                 self._not_writeable = not_writeable
             case _:
-                raise ValueError(
-                    f"Invalid mode '{mode}'. Must be None, 'read', or 'write'."
-                )
+                raise ValueError(f"Invalid mode '{mode}'. Must be None, 'read', or 'write'.")
 
         # Handle cwd_only flag (independent of mode)
         self._cwd_only = cwd_only
@@ -466,9 +464,7 @@ def _check_cwd_traversal(self, path_obj: Path | None = None) -> bool:
             # If other resolution fails, treat as dangerous
             return True
 
-    def _check_against_paths(
-        self, paths: list[str], path_obj: Path | None = None
-    ) -> bool:
+    def _check_against_paths(self, paths: list[str], path_obj: Path | None = None) -> bool:
         """Check if a path matches any in the given list.
 
         Args:
@@ -524,9 +520,7 @@ def _check_invalid_chars(self, path_str: str | None = None) -> bool:
 
         return False
 
-    def __call__(
-        self, path: str | Path | None = None, raise_error: bool = False
-    ) -> bool:
+    def __call__(self, path: str | Path | None = None, raise_error: bool = False) -> bool:
         """Check a path for danger, with optional path reload.
 
         Note: Unlike the boolean context (which returns True for safe paths),
@@ -594,9 +588,7 @@ def __call__(
                 is_dangerous = True
 
             if is_dangerous and raise_error:
-                raise DangerousPathError(
-                    f"Path '{path}' points to a dangerous location"
-                )
+                raise DangerousPathError(f"Path '{path}' points to a dangerous location")
 
             return is_dangerous
         else:
@@ -605,9 +597,7 @@ def __call__(
             is_dangerous = self._is_dangerous()
 
             if is_dangerous and raise_error:
-                raise DangerousPathError(
-                    f"Path '{self._path}' points to a dangerous location"
-                )
+                raise DangerousPathError(f"Path '{self._path}' points to a dangerous location")
 
             return is_dangerous
 
@@ -966,6 +956,4 @@ def __new__(
         cwd_only: bool = False,
     ) -> BasePathChecker:
         """Create a platform-specific PathChecker instance."""
-        return _create_path_checker(
-            path, raise_error, mode, system_ok, user_paths_ok, not_writeable, cwd_only
-        )
+        return _create_path_checker(path, raise_error, mode, system_ok, user_paths_ok, not_writeable, cwd_only)
diff --git a/bad_path/platforms/windows/checker.py b/bad_path/platforms/windows/checker.py
index 271bec9..99acde4 100644
--- a/bad_path/platforms/windows/checker.py
+++ b/bad_path/platforms/windows/checker.py
@@ -108,11 +108,7 @@ def _check_invalid_chars(self, path_str: str | None = None) -> bool:
                 if char == ":":
                     # Check if colon is part of a drive letter (e.g., C:, D:)
                     # Valid pattern: single letter followed by colon at start of path
-                    if (
-                        len(path_str) >= 2
-                        and path_str[1] == ":"
-                        and path_str[0].isalpha()
-                    ):
+                    if len(path_str) >= 2 and path_str[1] == ":" and path_str[0].isalpha():
                         # This is a valid drive letter if it's the only colon
                         if path_str.count(":") == 1:
                             continue  # This is a valid drive letter colon
diff --git a/docs/conf.py b/docs/conf.py
index 44888b6..5ea9f19 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -7,21 +7,22 @@
 import sys
 
 # Add the package to the path
-sys.path.insert(0, os.path.abspath('..'))
+sys.path.insert(0, os.path.abspath(".."))
 
 # Import version from package
 from bad_path import __version__
 
 # Add sphinx-better-theme to the path
 import better
+
 html_theme_path = [better.better_theme_path]
 
 # -- Project information -----------------------------------------------------
 # https://www.sphinx-doc.org/en/master/usage/configuration.html#project-information
 
-project = 'bad_path'
-project_copyright = '2026, Gavin Burnell'
-author = 'Gavin Burnell'
+project = "bad_path"
+project_copyright = "2026, Gavin Burnell"
+author = "Gavin Burnell"
 release = __version__
 version = __version__
 
@@ -29,44 +30,44 @@
 # https://www.sphinx-doc.org/en/master/usage/configuration.html#general-configuration
 
 extensions = [
-    'sphinx.ext.autodoc',
-    'sphinx.ext.napoleon',
-    'sphinx.ext.viewcode',
-    'sphinx.ext.intersphinx',
+    "sphinx.ext.autodoc",
+    "sphinx.ext.napoleon",
+    "sphinx.ext.viewcode",
+    "sphinx.ext.intersphinx",
 ]
 
-templates_path = ['_templates']
-exclude_patterns = ['_build', 'Thumbs.db', '.DS_Store']
+templates_path = ["_templates"]
+exclude_patterns = ["_build", "Thumbs.db", ".DS_Store"]
 
 # -- Options for HTML output -------------------------------------------------
 # https://www.sphinx-doc.org/en/master/usage/configuration.html#options-for-html-output
 
-html_theme = 'better'
-html_static_path = ['_static']
+html_theme = "better"
+html_static_path = ["_static"]
 
 # Theme options for sphinx-better-theme
 html_theme_options = {
-    'rightsidebar': False,
-    'inlinecss': '',
-    'linktotheme': False,
+    "rightsidebar": False,
+    "inlinecss": "",
+    "linktotheme": False,
 }
 
 # Use organization logo
-html_logo = '_static/StonerLogo2.png'
+html_logo = "_static/StonerLogo2.png"
 
 # -- Options for intersphinx extension ---------------------------------------
 # https://www.sphinx-doc.org/en/master/usage/extensions/intersphinx.html#configuration
 
 intersphinx_mapping = {
-    'python': ('https://docs.python.org/3', None),
+    "python": ("https://docs.python.org/3", None),
 }
 
 # -- Options for autodoc extension -------------------------------------------
 
 autodoc_default_options = {
-    'members': True,
-    'member-order': 'bysource',
-    'special-members': '__init__',
-    'undoc-members': True,
-    'exclude-members': '__weakref__'
+    "members": True,
+    "member-order": "bysource",
+    "special-members": "__init__",
+    "undoc-members": True,
+    "exclude-members": "__weakref__",
 }
diff --git a/pyproject.toml b/pyproject.toml
index c6aa7f1..b86f280 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -36,6 +36,8 @@ dev = [
     "sphinx>=7.0",
     "sphinx-better-theme>=0.1.5",
     "ruff>=0.1.0",
+    "black>=24.0",
+    "pre-commit>=3.0",
 ]
 
 [project.urls]
@@ -76,6 +78,10 @@ exclude_lines = [
     "if TYPE_CHECKING:",
 ]
 
+[tool.black]
+line-length = 119
+target-version = ['py310', 'py311', 'py312', 'py313']
+
 [tool.ruff]
 line-length = 100
 target-version = "py310"
diff --git a/tests/test_invalid_characters.py b/tests/test_invalid_characters.py
index 88ca05f..c459ba6 100644
--- a/tests/test_invalid_characters.py
+++ b/tests/test_invalid_characters.py
@@ -83,7 +83,7 @@ def test_windows_invalid_chars():
     if platform.system() != "Windows":
         pytest.skip("Windows-specific test")
 
-    invalid_chars = ['<', '>', ':', '"', '|', '?', '*']
+    invalid_chars = ["<", ">", ":", '"', "|", "?", "*"]
     for char in invalid_chars:
         checker = PathChecker(f"C:\\tmp\\test{char}file.txt")
         assert checker.has_invalid_chars is True, f"Character '{char}' should be invalid"
diff --git a/tests/test_path_checker_flags.py b/tests/test_path_checker_flags.py
index a3752ae..dc2c050 100644
--- a/tests/test_path_checker_flags.py
+++ b/tests/test_path_checker_flags.py
@@ -188,9 +188,7 @@ def test_invalid_chars_always_dangerous():
         test_path = "/tmp/test\x00file.txt"  # nosec B108
 
     # Invalid chars should be dangerous even with all flags enabled
-    checker = PathChecker(
-        test_path, system_ok=True, user_paths_ok=True, not_writeable=True
-    )
+    checker = PathChecker(test_path, system_ok=True, user_paths_ok=True, not_writeable=True)
     assert not checker  # Still dangerous
     assert checker.has_invalid_chars
 
diff --git a/tests/test_path_checker_mode.py b/tests/test_path_checker_mode.py
index 61cd342..95789f4 100644
--- a/tests/test_path_checker_mode.py
+++ b/tests/test_path_checker_mode.py
@@ -106,9 +106,7 @@ def test_mode_none_respects_individual_flags():
         system_path = "/etc/passwd"
 
     # mode=None with flags should work like before
-    checker = PathChecker(
-        system_path, mode=None, system_ok=True, not_writeable=True
-    )
+    checker = PathChecker(system_path, mode=None, system_ok=True, not_writeable=True)
     assert checker  # Safe with flags