diff --git a/AOC2021.Test/AOC2021.Test.csproj b/AOC2021.Test/AOC2021.Test.csproj
index 077343f..0e8762c 100644
--- a/AOC2021.Test/AOC2021.Test.csproj
+++ b/AOC2021.Test/AOC2021.Test.csproj
@@ -36,6 +36,12 @@
     <None Update="Input\Day3_test.txt">
       <CopyToOutputDirectory>Always</CopyToOutputDirectory>
     </None>
+    <None Update="Input\Day4_input.txt">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </None>
+    <None Update="Input\Day4_test.txt">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </None>
   </ItemGroup>
 
 </Project>
diff --git a/AOC2021.Test/DayTest.cs b/AOC2021.Test/DayTest.cs
index 8b1aef5..a4ab03c 100644
--- a/AOC2021.Test/DayTest.cs
+++ b/AOC2021.Test/DayTest.cs
@@ -38,5 +38,13 @@ namespace AOC2021.Tests
             var result = _tester.Test(request);
             Assert.IsTrue(request.Answer.Equals(result.Answer));
         }
+
+        [TestMethod]
+        public void Day4()
+        {
+            var request = new TestRequest() { Day = "day4", Answer = new Answer() { Day_A_Test = "4512", Day_A_Input = "63424", Day_B_Test = "1924", Day_B_Input = "23541" } };
+            var result = _tester.Test(request);
+            Assert.IsTrue(request.Answer.Equals(result.Answer));
+        }
     }
 }
diff --git a/AOC2021.Test/Input/Day4_input.txt b/AOC2021.Test/Input/Day4_input.txt
new file mode 100644
index 0000000..9c7ad40
--- /dev/null
+++ b/AOC2021.Test/Input/Day4_input.txt
@@ -0,0 +1,601 @@
+63,23,2,65,55,94,38,20,22,39,5,98,9,60,80,45,99,68,12,3,6,34,64,10,70,69,95,96,83,81,32,30,42,73,52,48,92,28,37,35,54,7,50,21,74,36,91,97,13,71,86,53,46,58,76,77,14,88,78,1,33,51,89,26,27,31,82,44,61,62,75,66,11,93,49,43,85,0,87,40,24,29,15,59,16,67,19,72,57,41,8,79,56,4,18,17,84,90,47,25
+
+25 29 78 57 69
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+ 9 37 48 71 91
+
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+
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+
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+46  8 36  9 42
+ 3 32 49 64 48
+15  2 47 53 55
+
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+33 11 65 76 13
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+95 78 51 74  4
+80 14 44 98 58
+
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+20 53 72 50 70
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+
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+
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+
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+
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+
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+60  8 56 86 32
+95 89 71 51 59
+87  3 27 44 41
+
+ 9 71 95 12 42
+83 90 98 79 49
+72  1 53 80 33
+29 82 65  4 25
+92  5 76 54 66
+
+72 85  4 39 29
+86  0 95 30 21
+11 51  2 99 38
+58 52 25 59 77
+69 74 37 87 32
+
+99 16  9 63 55
+79 50 48 96 92
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+19 70 25 49 38
+80 60 43 69 81
+
+50 19 10  7 83
+79 52 14 51 55
+68 65 54 21 62
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+44 26 61  4 46
+
+75 26 15 76 61
+42  0 51 29 81
+82 57 16 91  4
+12 19 30 10 24
+78 58 55 74 53
+
+36 80 46  9 85
+34 17 43 96 57
+37  6 33 88 28
+59 48 18 22 79
+55 52 20  2 61
+
+ 3 99 46  7 31
+61 43 17 78  4
+59 45 47 52 10
+55 95 33  9 35
+13  8 89 73 12
+
+19 58 46 56 62
+11 72 82  0 12
+92  9 70 18 65
+35 61 79 87 36
+ 1 27 22  8 74
+
+60 92 94  2 84
+73 69 72 29 37
+50 74 56 58  6
+51 80 86 33  4
+32 24 20  7 78
+
+47 25 76 89 61
+86 77 71 43 22
+42 18 70 24 98
+31 68 62 79  9
+17 10 78 16 84
+
+90 41 71  1 58
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+48 31  3 74 21
+85  5 37 36 28
+18 46 17 49 69
+
+41 55 52 58 44
+ 4 75 81 12 48
+72 93  8 86 10
+66 29 94 85 69
+74 36 50  9 19
+
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+58  8 27 18 86
+79  5 48 82 64
+ 0 93 30  1  4
+78 40 52 50 62
+
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+
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+
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+
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+
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+
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+
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+
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+
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+
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+
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+
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+
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+
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+
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+
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+
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+
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+
+54  8 72 38 29
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+
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+
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+
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+
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+
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+
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+
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+
+25 91 46 84 66
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+63 29 79 51 53
+70 69 61 80 54
+
+19 11 24  9 93
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+92 76 94 86  1
+
+51 31 27 28 95
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+ 1 11 79 45 90
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+
+58  0 63 88 30
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+
+96 20  7 81 11
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+15 57 80  3 67
+61 66 38 83 59
+
+ 3 60 25 55 17
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+13 16 41 11 88
+89 96 97 35  1
+83  5 52 69 28
+
+99 11 53 82  3
+88 74 42 38 13
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+29 56  8 14 76
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+
+80 82 43 87 70
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+
+53 41 29 77 58
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+
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+
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+
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+
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+
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+
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+
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+
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+
+24  9  5 38 52
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+31 76 96 65  0
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+
+19 37 39 15 86
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+ 9 26 84 93 10
+33 25 61 21  0
+34 60 30 99  7
+
+62 50 33 29 54
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+60  2 27  7  9
+28 18 31 35 59
+20 63 38 72 14
+
+96 89 34 56 63
+61  8 25 90 78
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+ 1 32  7 83 73
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+
+44 59 87 16 18
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+13 24 91 46 70
+22 37  6 43 25
+
+87 79 59 26 35
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+24 94 71 91 48
+12 77 93 55 34
+
+91 93 56 55 58
+24 11 82 35 86
+68 81 50 34 23
+59 73  1  8 37
+18 83 80 53 85
+
+40 30  7 72 22
+68 94 95 89 42
+91 84 11 49 36
+64 29 26 73 76
+37  1 51  9 25
+
+32 48 47 36 88
+54 91 59 72 50
+31 83 19 20  0
+24 67 61 46 99
+52 53 11 16 69
+
+86 52 95 73  6
+56 45  8 13 80
+28 77 19 59 48
+99 33 47 10 85
+35 81 27 46 76
+
+41 45  1 12 49
+32 16 21 85 27
+50 80 66 64 10
+76 11  9 59 52
+71 37 34  2 43
+
+43 19 88 81 12
+ 4 48  9 91 31
+ 1 46 10  6 56
+72 41 30 36 94
+61 83 86 28 79
+
+39 10 40 25 52
+29 60 38 18 31
+65 46 11  0 94
+68 12 42  4 84
+55 20 86 77 26
+
+12 65 79 59 43
+93  6 68  1 29
+17 48 45 26 80
+37 22  5 66 47
+71 11 41 18 64
+
+ 5 45 54 82 64
+90 89 22 17 71
+81 60 65 32 34
+41 86 35 30 48
+67 47 23 51  6
+
+19 65 11 58 49
+97 68 56 10 39
+87 29 43 40 83
+ 9 41 26 79 77
+63 72 93  4 51
+
+82 50 90 45  4
+53 96 93 30 19
+ 8 95 73 74 98
+35 20 32  7 36
+56 52 59 26 16
+
+94 67 97 34 75
+23 80 68 24 47
+56  8 21 66 36
+69  5  3 95 17
+29 38 44 42 28
+
+84 35 72  8 38
+94 30 48 24 27
+81 61 18 87 90
+65 17 85 22 45
+32 15 74 52 68
+
+ 9 69 63 68 36
+44 31 35 12 39
+57 83  6 49 23
+64  0 10 85 81
+82 40 34 91 24
\ No newline at end of file
diff --git a/AOC2021.Test/Input/Day4_test.txt b/AOC2021.Test/Input/Day4_test.txt
new file mode 100644
index 0000000..cabc5cc
--- /dev/null
+++ b/AOC2021.Test/Input/Day4_test.txt
@@ -0,0 +1,19 @@
+7,4,9,5,11,17,23,2,0,14,21,24,10,16,13,6,15,25,12,22,18,20,8,19,3,26,1
+
+22 13 17 11  0
+ 8  2 23  4 24
+21  9 14 16  7
+ 6 10  3 18  5
+ 1 12 20 15 19
+
+ 3 15  0  2 22
+ 9 18 13 17  5
+19  8  7 25 23
+20 11 10 24  4
+14 21 16 12  6
+
+14 21 17 24  4
+10 16 15  9 19
+18  8 23 26 20
+22 11 13  6  5
+ 2  0 12  3  7
\ No newline at end of file
diff --git a/AOC2021/Controllers/AdventOfCodeController.cs b/AOC2021/Controllers/AdventOfCodeController.cs
index 5e66724..e08ab44 100644
--- a/AOC2021/Controllers/AdventOfCodeController.cs
+++ b/AOC2021/Controllers/AdventOfCodeController.cs
@@ -22,6 +22,7 @@ namespace AOC2021.Controllers
         [Route("day1")]
         [Route("day2")]
         [Route("day3")]
+        [Route("day4")]
         public AOCResponse Day(AOCVersion version, [FromBody] string input, bool IgnoreLogMessages = false)
         {
             AOCRequest request = new AOCRequest() { Input = input, Version = version, IgnoreLogMessages = IgnoreLogMessages };
diff --git a/AOC2021/Days/Day4.cs b/AOC2021/Days/Day4.cs
new file mode 100644
index 0000000..7757fb7
--- /dev/null
+++ b/AOC2021/Days/Day4.cs
@@ -0,0 +1,86 @@
+using AOC2021.Helper;
+using AOC2021.Models;
+using AOC2021.Models.Day4;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace AOC2021.Days
+{
+    public class Day4 : AOCDay
+    {
+        private static readonly int BOARD_SIZE = 5;
+        private List<BingoBoard> _boards;
+        public Day4()
+        {
+            _boards = new List<BingoBoard>();
+        }
+        protected override AOCResponse ExecutePartA()
+        {
+            var input = GetSplitInput();
+            var checkedValues = input.First().Trim().Split(","); //Save selected answers into variable
+            CreateBoards(input);
+
+            BingoBoard winner = null;
+            foreach (var ball in checkedValues)
+            {
+                Log("Ball picked was " + ball);
+                foreach (var board in _boards)
+                {
+                    board.MarkValueAsChecked(ball.ToInt());
+                    if (board.IsWinner())
+                    {
+                        winner = board;
+                        Log("We have a winning board, number " + winner.Id);
+                        break;
+                    }
+                }
+                if (winner != null)
+                    break;
+            }
+            this._response.Answer = winner.CalculateScore().ToString();
+            Log("Winning board score is " + this._response.Answer);
+
+            return this._response;
+        }
+
+        protected override AOCResponse ExecutePartB()
+        {
+            var input = GetSplitInput();
+            var checkedValues = input.First().Trim().Split(","); //Save selected answers into variable
+            CreateBoards(input);
+
+            BingoBoard winner = null;
+            foreach (var ball in checkedValues)
+            {
+                Log("Ball picked was " + ball);
+                foreach (var board in _boards.Reverse<BingoBoard>())
+                {
+                    board.MarkValueAsChecked(ball.ToInt());
+                    if (board.IsWinner())
+                    {
+                        winner = board;
+                        _boards.Remove(board);
+                    }
+                }
+            }
+            this._response.Answer = winner.CalculateScore().ToString();
+            Log("Winning board score is " + this._response.Answer);
+            return this._response;
+        }
+
+        private void CreateBoards(string[] input)
+        {
+            //Create all of our game boards
+            int skipValue = 2;
+            while (skipValue < input.Length)
+            {
+                var group = input.Skip(skipValue).Take(5);
+                _boards.Add(new BingoBoard(BOARD_SIZE, group));
+                skipValue += 6;
+            }
+
+        }
+    }
+}
diff --git a/AOC2021/Models/Day4/BingoBoard.cs b/AOC2021/Models/Day4/BingoBoard.cs
new file mode 100644
index 0000000..28710dd
--- /dev/null
+++ b/AOC2021/Models/Day4/BingoBoard.cs
@@ -0,0 +1,104 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace AOC2021.Models.Day4
+{
+    public class BingoBoard
+    {
+        private static int ID_COUNT = 1;
+        public int Id;
+        private int _size;
+        private List<BingoSpot> _board;
+        private int _lastAnswer;
+        public BingoBoard(int size, IEnumerable<string> values)
+        {
+            Id = ID_COUNT++;
+            _size = size;
+            _board = new List<BingoSpot>();
+            ConstructBoard(values);
+        }
+
+        private void ConstructBoard(IEnumerable<string> values)
+        {
+            for (int x = 0; x < values.Count(); x++)
+            {
+                var splitValue = values.ElementAt(x).Trim().Replace("  ", " ").Split(" ");
+                for (int y = 0; y < splitValue.Length; y++)
+                {
+                    _board.Add(new BingoSpot()
+                    {
+                        Checked = false,
+                        Value = Convert.ToInt32(splitValue[y]),
+                        X = x,
+                        Y = y
+                    });
+                }
+            }
+        }
+
+        private BingoSpot SpotAt(int x, int y)
+        {
+            foreach (var bs in _board)
+                if (bs.X == x && bs.Y == y)
+                    return bs;
+            throw new Exception($"Can't find spot {x},{y} in the bingo board!");
+        }
+
+        public void MarkValueAsChecked(int value)
+        {
+
+            foreach (var bs in _board)
+                if (bs.Value == value)
+                {
+                    bs.Checked = true;
+                }
+            _lastAnswer = value;
+        }
+
+        public string PrintBoard()
+        {
+            var boardPrintout = string.Empty;
+            for (int x = 0; x < _size; x++)
+            {
+                var line = string.Empty;
+                for (int y = 0; y < _size; y++)
+                {
+                    line += $"{SpotAt(x, y).Value} ";
+                }
+                boardPrintout += $"{line}{Environment.NewLine}";
+            }
+            return boardPrintout;
+        }
+
+        public bool IsWinner()
+        {
+            for (int x = 0; x < _size; x++)
+            {
+                //If its still checked, and the next spot is NOT checked set to false and ends the check
+                bool horizontalRow = true;
+                bool verticalRow = true;
+                for (int y = 0; y < _size; y++)
+                {
+                    if (horizontalRow && !SpotAt(x, y).Checked)
+                        horizontalRow = false;
+                    if (verticalRow && !SpotAt(y, x).Checked)
+                        verticalRow = false;
+                }
+                if (horizontalRow || verticalRow)
+                    return true;
+            }
+            return false;
+        }
+
+        public int CalculateScore()
+        {
+            int unMarked = 0;
+            foreach (var x in _board)
+                if (!x.Checked)
+                    unMarked += x.Value;
+            return unMarked * _lastAnswer;
+        }
+    }
+}
diff --git a/AOC2021/Models/Day4/BingoSpot.cs b/AOC2021/Models/Day4/BingoSpot.cs
new file mode 100644
index 0000000..e2b03f2
--- /dev/null
+++ b/AOC2021/Models/Day4/BingoSpot.cs
@@ -0,0 +1,10 @@
+namespace AOC2021.Models.Day4
+{
+    public class BingoSpot
+    {
+        public int Value { get; set; }
+        public int X { get; set; }
+        public int Y { get; set; }
+        public bool Checked { get; set; }
+    }
+}