diff --git a/lib/binary_kata.ex b/lib/binary_kata.ex
index eb75fef..5a749c1 100644
--- a/lib/binary_kata.ex
+++ b/lib/binary_kata.ex
@@ -4,17 +4,19 @@ defmodule BinaryKata do
   Should return `true` when given parameter start with UTF8 Byte-Order-Mark, otherwise `false`.
   @see https://en.wikipedia.org/wiki/Byte_order_mark
   """
-  def has_utf8_bom?(_), do: raise "TODO: Implement me!"
+  def has_utf8_bom?(<<239, 187, 191, _::binary>>), do: true
+  def has_utf8_bom?(_), do: false
 
   @doc """
   Remove a UTF8 BOM if exists.
   """
-  def remove_utf8_bom(_), do: raise "TODO: Implement me!"
+  def remove_utf8_bom(<<239, 187, 191, content::binary>>), do: content
+  def remove_utf8_bom(content), do: content
 
   @doc """
   Add a UTF8 BOM if not exists.
   """
-  def add_utf8_bom(_), do: raise "TODO: Implement me!"
+  def add_utf8_bom(content), do: <<239, 187, 191>> <> remove_utf8_bom(content)
 
   @doc """
   Detecting types of images by their first bytes / magic numbers.
@@ -23,7 +25,10 @@ defmodule BinaryKata do
   @see https://en.wikipedia.org/wiki/Portable_Network_Graphics
   @see https://en.wikipedia.org/wiki/GIF
   """
-  def image_type!(_), do: raise "TODO: Implement me!"
+  def image_type!(<<0xFF, 0xD8, _::binary>>), do: :jfif
+  def image_type!(<<0x89, 0x50, 0x4E, 0x47, _::binary>>), do: :png
+  def image_type!(<<0x47, 0x49, 0x46, 0x38, 0x39, 0x61, _::binary>>), do: :gif
+  def image_type!(_), do: :unknown
 
   @doc """
   Get the width and height from a GIF image.
@@ -32,15 +37,34 @@ defmodule BinaryKata do
   `width` will be little-endian in byte 7 and 8.
   `height` will be little-endian in byte 9 and 10.
   """
-  def gif_dimensions!(_), do: raise "TODO: Implement me!"
+  def gif_dimensions!(<<0x47, 0x49, 0x46, 0x38, 0x39, 0x61, width::little-size(16), height::little-size(16), _::binary>>), do: {width, height}
+  def gif_dimensions!(_), do: :error
 
   @doc """
   Parsing Payload of a ARP packet. Padding will be omitted.
 
   @see https://en.wikipedia.org/wiki/Address_Resolution_Protocol
   """
-  def parse_arp_packet_ipv4!(_) do
-      raise "TODO: Implement me!"
+  def parse_arp_packet_ipv4!(<<
+    # Defined values for IPv4
+    1::size(16),
+    2048::size(16),
+    6::size(8),
+    4::size(8),
+    # Payload
+    operation::size(16),
+    src_mac_addr::size(48),
+    src_ip_addr_1, src_ip_addr_2, src_ip_addr_3, src_ip_addr_4,
+    target_mac_addr::size(48),
+    target_ip_addr_1, target_ip_addr_2, target_ip_addr_3, target_ip_addr_4,
+    _padding::binary>>) do
+    {
+      operation |> arp_operation_to_atom,
+      src_mac_addr,
+      {src_ip_addr_1, src_ip_addr_2, src_ip_addr_3, src_ip_addr_4},
+      target_mac_addr,
+      {target_ip_addr_1, target_ip_addr_2, target_ip_addr_3, target_ip_addr_4}
+    }
   end
 
   # Helper for `parse_arp_packet_ipv4!`