diff --git a/LeetCode/problem067_AddBinary.go b/LeetCode/problem067_AddBinary.go
new file mode 100644
index 0000000..4a559fb
--- /dev/null
+++ b/LeetCode/problem067_AddBinary.go
@@ -0,0 +1,36 @@
+package leetcode
+
+// Time complexity: O(n)
+// Space complexity: O(n)
+func addBinary(a string, b string) string {
+	i, j := len(a)-1, len(b)-1
+	carry := 0
+	res := make([]byte, 0, maxInt(len(a), len(b))+1)
+
+	for i >= 0 || j >= 0 || carry > 0 {
+		sum := carry
+		if i >= 0 {
+			sum += int(a[i] - '0')
+			i--
+		}
+		if j >= 0 {
+			sum += int(b[j] - '0')
+			j--
+		}
+		res = append(res, byte(sum%2)+'0')
+		carry = sum / 2
+	}
+
+	for l, r := 0, len(res)-1; l < r; l, r = l+1, r-1 {
+		res[l], res[r] = res[r], res[l]
+	}
+	return string(res)
+}
+
+// Helper function
+func maxInt(x, y int) int {
+	if x > y {
+		return x
+	}
+	return y
+}
diff --git a/LeetCode/problem067_AddBinary_test.go b/LeetCode/problem067_AddBinary_test.go
new file mode 100644
index 0000000..048ea53
--- /dev/null
+++ b/LeetCode/problem067_AddBinary_test.go
@@ -0,0 +1,25 @@
+package leetcode
+
+import "testing"
+
+func TestAddBinary(t *testing.T) {
+	tests := []struct {
+		a, b     string
+		expected string
+	}{
+		{"11", "1", "100"},
+		{"1010", "1011", "10101"},
+		{"0", "0", "0"},
+		{"1", "0", "1"},
+		{"111", "111", "1110"},
+		{"110010", "10111", "1001001"},
+		{"1111111111111111", "1", "10000000000000000"},
+	}
+
+	for _, tt := range tests {
+		result := addBinary(tt.a, tt.b)
+		if result != tt.expected {
+			t.Errorf("addBinary(%q, %q) = %q; want %q", tt.a, tt.b, result, tt.expected)
+		}
+	}
+}