diff --git a/src/pkgmt/fail_if_modified.py b/src/pkgmt/fail_if_modified.py
new file mode 100644
index 0000000..c462b9a
--- /dev/null
+++ b/src/pkgmt/fail_if_modified.py
@@ -0,0 +1,48 @@
+import subprocess
+import argparse
+import sys
+
+
+def check_modified(base_branch, exclude_path, debug=False):
+    # https://stackoverflow.com/questions/4380945
+    cmd = f"git diff --exit-code {base_branch}... -- ."
+
+    for path in exclude_path:
+        cmd += f" ':^{path}'"
+
+    if debug:
+        print(f"cmd: {cmd}")
+    try:
+        subprocess.check_output(cmd, shell=True)
+        return 0
+    except subprocess.CalledProcessError as err:
+        if debug:
+            print(
+                f"Path has been modified with respect to '{base_branch}'\n"
+                f"Excluding paths: {exclude_path}"
+            )
+            print(f"Return code: {err.returncode}")
+            print(f"Output: {err.output}")
+        return 1
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(
+        description="Check if a branch has modified" "anything excluding some path/dir"
+    )
+    parser.add_argument(
+        "-b", "--base-branch", default="main", help="Base branch to compare against"
+    )
+    parser.add_argument(
+        "-e",
+        "--exclude-path",
+        default=["doc"],
+        nargs="+",
+        help="Path to exclude from git diff."
+        "Can be used multiple times eg: -e p1 -e p2",
+    )
+    parser.add_argument("--debug", action="store_true", help="Print debug info")
+
+    args = parser.parse_args()
+    returncode = check_modified(args.base_branch, args.exclude_path, debug=args.debug)
+    sys.exit(returncode)
diff --git a/tests/conftest.py b/tests/conftest.py
index 584ffd5..e2b5fe7 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -57,3 +57,69 @@ def tmp_another_package(root, tmp_empty):
     yield tmp_empty
 
     os.chdir(old)
+
+
+@pytest.fixture
+def tmp_package_modi(root, tmp_empty):
+    old = Path.cwd()
+    path_to_templates = root / "tests" / "assets" / "package_name"
+
+    shutil.copytree(str(path_to_templates), "copy")
+    os.chdir("copy")
+
+    subprocess.run(["git", "init"])
+    subprocess.check_call(["git", "config", "commit.gpgsign", "false"])
+    subprocess.check_call(["git", "config", "user.email", "ci@ploomberio"])
+    subprocess.check_call(["git", "config", "user.name", "Ploomber"])
+    subprocess.run(["git", "checkout", "-b", "main"])
+    subprocess.run(["git", "add", "--all"])
+    subprocess.run(["git", "commit", "-m", "init-commit-message"])
+
+    subprocess.run(["git", "checkout", "-b", "test_modified_doc"])
+    Path.cwd().joinpath("test_doc1").mkdir(parents=True, exist_ok=True)
+    Path.cwd().joinpath("test_doc1", "test_modified.txt").touch()
+    Path.cwd().joinpath("test_doc2").mkdir(parents=True, exist_ok=True)
+    Path.cwd().joinpath("test_doc2", "test_modified.txt").touch()
+    subprocess.run(["git", "add", "."])
+    subprocess.run(["git", "commit", "-m", "test_modified"])
+
+    yield tmp_empty
+
+    os.chdir(old)
+
+
+@pytest.fixture
+def tmp_package_modi_2(root, tmp_empty):
+    old = Path.cwd()
+    path_to_templates = root / "tests" / "assets" / "package_name"
+    shutil.copytree(str(path_to_templates), "copy")
+    os.chdir("copy")
+
+    subprocess.run(["git", "init"])
+    subprocess.check_call(["git", "config", "commit.gpgsign", "false"])
+    subprocess.check_call(["git", "config", "user.email", "ci@ploomberio"])
+    subprocess.check_call(["git", "config", "user.name", "Ploomber"])
+    subprocess.run(["git", "checkout", "-b", "main"])
+    subprocess.run(["git", "add", "--all"])
+    subprocess.run(["git", "commit", "-m", "init-commit-message"])
+
+    Path.cwd().joinpath("doc").mkdir(parents=True, exist_ok=True)
+    Path.cwd().joinpath("doc", "file.txt").touch()
+    subprocess.run(["git", "add", "."])
+    subprocess.run(["git", "commit", "-m", "added doc/file.txt"])
+
+    subprocess.run(["git", "checkout", "-b", "test_modified_doc"])
+    Path.cwd().joinpath("doc").mkdir(parents=True, exist_ok=True)
+    Path.cwd().joinpath("doc", "another.txt").touch()
+    subprocess.run(["git", "add", "."])
+    subprocess.run(["git", "commit", "-m", "add doc/another.txt"])
+
+    subprocess.run(["git", "checkout", "main"])
+    Path.cwd().joinpath("something").mkdir(parents=True, exist_ok=True)
+    Path.cwd().joinpath("something", "file.txt").touch()
+    subprocess.run(["git", "add", "."])
+    subprocess.run(["git", "commit", "-m", "added something/file.txt"])
+
+    yield tmp_empty
+
+    os.chdir(old)
diff --git a/tests/test_modified.py b/tests/test_modified.py
new file mode 100644
index 0000000..aa2f14a
--- /dev/null
+++ b/tests/test_modified.py
@@ -0,0 +1,28 @@
+import pytest
+from pkgmt import fail_if_modified
+
+
+@pytest.mark.parametrize(
+    "base_branch, exclude_path, returncode",
+    [
+        [
+            "main",
+            ["test_doc1"],
+            1,
+        ],
+        [
+            "main",
+            ["test_doc1", "test_doc2"],
+            0,
+        ],
+    ],
+)
+def test_check_modified(tmp_package_modi, base_branch, exclude_path, returncode):
+    assert (
+        fail_if_modified.check_modified(base_branch, exclude_path, debug=True)
+        == returncode
+    )
+
+
+def test_check_modified_2(tmp_package_modi_2):
+    assert fail_if_modified.check_modified("main", ["doc"], debug=True) == 0