diff --git a/2021/.input/day13 b/2021/.input/day13
new file mode 100644
index 0000000..b35da5c
--- /dev/null
+++ b/2021/.input/day13
@@ -0,0 +1,789 @@
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+
+fold along x=655
+fold along y=447
+fold along x=327
+fold along y=223
+fold along x=163
+fold along y=111
+fold along x=81
+fold along y=55
+fold along x=40
+fold along y=27
+fold along y=13
+fold along y=6
diff --git a/2021/Python/day13.py b/2021/Python/day13.py
new file mode 100644
index 0000000..03af788
--- /dev/null
+++ b/2021/Python/day13.py
@@ -0,0 +1,52 @@
+import re
+
+import numpy as np
+
+
+pattern_dots = re.compile(r"([0-9]+),([0-9]+)")
+pattern_folds = re.compile(r"fold along ([xy])=([0-9]+)")
+
+
+def load():
+    with open("../.input/day13") as f:
+        dots, folds = f.read().split("\n\n")
+    dots = [(int(x), int(y)) for x, y in pattern_dots.findall(dots)]
+    matrix = np.zeros((1 + max(y for _, y in dots), 1 + max(x for x, _ in dots)), dtype=bool)
+    for x, y in dots:
+        matrix[y, x] = True
+    return matrix, [(axis, int(offset)) for axis, offset in pattern_folds.findall(folds)]
+
+
+def fold(matrix: np.ndarray, axis, offset) -> np.ndarray:
+    if axis == "x":
+        result = matrix[:, :offset]
+        right = np.fliplr(matrix[:, offset+1:])
+        if result.shape == right.shape:
+            result |= right
+        else:
+            result[:, -right.shape[1]:] |= right
+    else:
+        result = matrix[:offset, :]
+        bottom = np.flipud(matrix[offset+1:, :])
+        if result.shape == bottom.shape:
+            result |= bottom
+        else:
+            result[-bottom.shape[0]:, :] |= bottom
+    return result
+
+
+def solve1() -> int:
+    dots, folds = load()
+    return fold(dots, *folds[0]).sum()
+
+
+def solve2() -> None:
+    dots, folds = load()
+    for axis, offset in folds:
+        dots = fold(dots, axis, offset)
+    [print("".join(line)) for line in np.where(dots, "#", " ")]
+
+
+if __name__ == "__main__":
+    print(solve1())  # 638
+    solve2()  # CJCKEBAPB