diff --git a/2021/day-13.py b/2021/day-13.py
new file mode 100644
index 0000000..d5d25e3
--- /dev/null
+++ b/2021/day-13.py
@@ -0,0 +1,118 @@
+# --- Day 13: Transparent Origami ---
+# https://adventofcode.com/2021/day/13
+
+import re
+
+
+def parse(input_data):
+    points, instructions = input_data.split("\n\n")
+    points = [list(map(int, point.split(","))) for point in points.splitlines()]
+
+    instructions = [
+        instruction.split()[-1].split("=") for instruction in instructions.splitlines()
+    ]
+    instructions = [(direction, int(n)) for direction, n in instructions]
+
+    return points, instructions
+
+
+def fold(point, instruction):
+    if instruction[0] == "y":
+        axis_num = 1
+    else:
+        axis_num = 0
+
+    if point[axis_num] > instruction[1]:
+        overage = point[axis_num] - instruction[1]
+        point[axis_num] = instruction[1] - overage
+
+    return point
+
+
+def fold_points(points, instruction):
+    new_points = []
+    for point in points:
+        new_point = fold(point, instruction)
+        if new_point not in new_points:
+            new_points.append(new_point)
+    return new_points
+
+
+def solve1(input_data):
+    points, instructions = parse(input_data)
+    new_points = fold_points(points, instructions[0])
+    return len(new_points)
+
+
+def fold_part_2(input_data):
+    points, instructions = parse(input_data)
+    new_points = points
+    for instruction in instructions:
+        new_points = fold_points(new_points, instruction)
+    return new_points
+
+
+def plot_points(points):
+    xs, ys = zip(*points)
+
+    xmax = max(xs)
+    ymax = max(ys)
+
+    for y in range(ymax + 1):
+        for x in range(xmax + 1):
+            if [x, y] in points:
+                print("#", end="")
+            else:
+                print(" ", end="")
+        print("\n", end="")
+
+
+def solve2(input_data):
+    points = fold_part_2(input_data)
+    return plot_points(points)
+
+
+if __name__ == "__main__":
+    from aocd.models import Puzzle
+
+    test_data = """6,10
+    0,14
+    9,10
+    0,3
+    10,4
+    4,11
+    6,0
+    6,12
+    4,1
+    0,13
+    10,12
+    3,4
+    3,0
+    8,4
+    1,10
+    2,14
+    8,10
+    9,0
+
+    fold along y=7
+    fold along x=5"""
+
+    assert solve1(test_data) == 17
+
+    puzzle = Puzzle(2021, 13)
+
+    answer_1 = solve1(puzzle.input_data)
+    print(answer_1)
+    puzzle.answer_a = answer_1
+
+    solve2(puzzle.input_data)
+    puzzle.answer_b = "BLKJRBAG"
+
+"""
+###  #    #  #   ## ###  ###   ##   ## 
+#  # #    # #     # #  # #  # #  # #  #
+###  #    ##      # #  # ###  #  # #   
+#  # #    # #     # ###  #  # #### # ##
+#  # #    # #  #  # # #  #  # #  # #  #
+###  #### #  #  ##  #  # ###  #  #  ###
+"""