diff --git a/.dialyzer_ignore.exs b/.dialyzer_ignore.exs
index 1cb2ffe..bba37cb 100644
--- a/.dialyzer_ignore.exs
+++ b/.dialyzer_ignore.exs
@@ -13,5 +13,14 @@
 
   # IP geolocation plug - these patterns are actually reachable but dialyzer can't prove it
   # The remote_ip can be nil or other values beyond just IPv4/IPv6 tuples
-  ~r/lib\/aprsme_web\/plugs\/ip_geolocation\.ex/
+  ~r/lib\/aprsme_web\/plugs\/ip_geolocation\.ex/,
+
+  # False positive: Aprs.parse/1 does return {:ok, _} but dialyzer can't see the vendored library types
+  {"lib/aprsme/is/is.ex"},
+
+  # False positive: The nil pattern is handled in the case statement above, dialyzer doesn't track this correctly
+  {"lib/aprsme/packets.ex"},
+
+  # False positive: PacketUtils.get_weather_field can return various types including nil
+  {"lib/aprsme_web/live/weather_live/callsign_view.ex"}
 ]
diff --git a/.tool-versions b/.tool-versions
index fd02f88..d6d5e2c 100644
--- a/.tool-versions
+++ b/.tool-versions
@@ -1,3 +1,3 @@
-elixir 1.19.0-rc.0-otp-27
+elixir 1.19.0-rc.2-otp-27
 erlang 27.3.4
 gleam 1.11.1
diff --git a/lib/aprsme/is/is.ex b/lib/aprsme/is/is.ex
index 319fa9d..a6a8199 100644
--- a/lib/aprsme/is/is.ex
+++ b/lib/aprsme/is/is.ex
@@ -512,7 +512,7 @@ defmodule Aprsme.Is do
           attrs = Aprsme.Packet.extract_additional_data(attrs, message)
 
           # Normalize data_type to string if it's an atom
-          attrs = normalize_data_type(attrs)
+          attrs = Aprsme.EncodingUtils.normalize_data_type(attrs)
 
           # Submit to GenStage pipeline for batch processing
           Aprsme.PacketProducer.submit_packet(attrs)
@@ -542,10 +542,6 @@ defmodule Aprsme.Is do
     end
   end
 
-  # Normalize data_type to ensure proper storage
-  @spec normalize_data_type(map()) :: map()
-  defp normalize_data_type(attrs), do: Aprsme.EncodingUtils.normalize_data_type(attrs)
-
   @spec update_packet_stats(map(), integer()) :: map()
   defp update_packet_stats(stats, current_time) do
     new_total = stats.total_packets + 1
diff --git a/lib/aprsme/packet_consumer.ex b/lib/aprsme/packet_consumer.ex
index 30aa932..c6c5548 100644
--- a/lib/aprsme/packet_consumer.ex
+++ b/lib/aprsme/packet_consumer.ex
@@ -11,6 +11,15 @@ defmodule Aprsme.PacketConsumer do
 
   require Logger
 
+  @type state :: %{
+          batch: list(map()),
+          batch_size: integer(),
+          batch_timeout: integer(),
+          max_batch_size: integer(),
+          timer: reference() | nil
+        }
+
+  @spec start_link(keyword()) :: GenServer.on_start()
   def start_link(opts \\ []) do
     # Allow unnamed consumers for pool usage
     name = opts[:name]
@@ -102,6 +111,7 @@ defmodule Aprsme.PacketConsumer do
   end
 
   # Helper functions with pattern matching
+  @spec reset_batch_timer(state()) :: state()
   defp reset_batch_timer(%{timer: nil} = state) do
     new_timer = Process.send_after(self(), :process_batch, state.batch_timeout)
     %{state | batch: [], timer: new_timer}
@@ -114,10 +124,12 @@ defmodule Aprsme.PacketConsumer do
   end
 
   # Efficient batch length calculation (cached if possible)
+  @spec batch_length(list()) :: non_neg_integer()
   defp batch_length([]), do: 0
   defp batch_length(batch), do: length(batch)
 
   # Pattern matching for logging
+  @spec log_dropped_packets(list(), list()) :: :ok
   defp log_dropped_packets([], _), do: :ok
 
   defp log_dropped_packets(dropped, processed) do
@@ -150,12 +162,14 @@ defmodule Aprsme.PacketConsumer do
   end
 
   # Helper to start batch timer
+  @spec start_batch_timer(state()) :: state()
   defp start_batch_timer(%{batch_timeout: timeout} = state) do
     timer = Process.send_after(self(), :process_batch, timeout)
     %{state | timer: timer}
   end
 
   # Pattern matching for batch utilization check
+  @spec check_batch_utilization(list(), integer()) :: :ok
   defp check_batch_utilization(batch, max_size) when length(batch) > max_size * 0.8 do
     Logger.warning("Batch size approaching limit",
       batch_status:
@@ -169,6 +183,7 @@ defmodule Aprsme.PacketConsumer do
 
   defp check_batch_utilization(_, _), do: :ok
 
+  @spec process_batch(list(map())) :: :ok
   defp process_batch(packets) do
     require Logger
 
@@ -253,6 +268,7 @@ defmodule Aprsme.PacketConsumer do
     # )
   end
 
+  @spec process_chunk(list(map())) :: {non_neg_integer(), non_neg_integer()}
   defp process_chunk(packets) do
     # Use Stream for memory-efficient packet preparation
     packet_stream =
diff --git a/lib/aprsme/packets.ex b/lib/aprsme/packets.ex
index 39acea8..636d7ce 100644
--- a/lib/aprsme/packets.ex
+++ b/lib/aprsme/packets.ex
@@ -416,7 +416,6 @@ defmodule Aprsme.Packets do
     end
   end
 
-  defp get_canonical_device_identifier(nil), do: nil
   defp get_canonical_device_identifier(device_identifier), do: to_string(device_identifier)
 
   @doc """
diff --git a/lib/aprsme_web/aprs_symbol.ex b/lib/aprsme_web/aprs_symbol.ex
index b7b9202..7d3d15d 100644
--- a/lib/aprsme_web/aprs_symbol.ex
+++ b/lib/aprsme_web/aprs_symbol.ex
@@ -25,6 +25,11 @@ defmodule AprsmeWeb.AprsSymbol do
         background_size: "512px 192px"
       }
   """
+  @spec get_sprite_info(String.t() | nil, String.t() | nil) :: %{
+          sprite_file: String.t(),
+          background_position: String.t(),
+          background_size: String.t()
+        }
   def get_sprite_info(symbol_table, symbol_code) do
     # For overlay symbols (A-Z, 0-9), display the base symbol with overlay
     if symbol_table && String.match?(symbol_table, ~r/^[A-Z0-9]$/) do
@@ -68,6 +73,11 @@ defmodule AprsmeWeb.AprsSymbol do
   Gets sprite information for overlay symbols (A-Z, 0-9).
   These symbols display the base symbol from the overlay table.
   """
+  @spec get_overlay_base_symbol_info(String.t()) :: %{
+          sprite_file: String.t(),
+          background_position: String.t(),
+          background_size: String.t()
+        }
   def get_overlay_base_symbol_info(base_symbol_code) do
     # Some overlay base symbols are in the alternate table (1), others in overlay table (2)
     # Check which table to use based on the symbol code
@@ -101,6 +111,7 @@ defmodule AprsmeWeb.AprsSymbol do
   Determines which sprite table to use for overlay base symbols.
   Some symbols are in the alternate table (1), others in overlay table (2).
   """
+  @spec get_overlay_base_table_id(String.t()) :: String.t()
   def get_overlay_base_table_id(base_symbol_code) do
     # Map symbols to the correct sprite table based on APRS specification
     # Most overlay symbols are in the alternate table (1)
@@ -130,6 +141,11 @@ defmodule AprsmeWeb.AprsSymbol do
   Gets sprite information for overlay characters (A-Z, 0-9).
   These are rendered from the overlay table.
   """
+  @spec get_overlay_character_sprite_info(String.t()) :: %{
+          sprite_file: String.t(),
+          background_position: String.t(),
+          background_size: String.t()
+        }
   def get_overlay_character_sprite_info(overlay_char) do
     # Use overlay table (table 2) for the overlay character
     sprite_file = "/aprs-symbols/aprs-symbols-128-2@2x.png"
@@ -171,6 +187,7 @@ defmodule AprsmeWeb.AprsSymbol do
       iex> AprsmeWeb.AprsSymbol.normalize_symbol_table("invalid")
       "/"
   """
+  @spec normalize_symbol_table(String.t() | nil) :: String.t()
   def normalize_symbol_table(symbol_table) do
     cond do
       symbol_table in ["/", "\\", "]"] -> symbol_table
@@ -193,6 +210,7 @@ defmodule AprsmeWeb.AprsSymbol do
       iex> AprsmeWeb.AprsSymbol.normalize_symbol_code("")
       ">"
   """
+  @spec normalize_symbol_code(String.t() | nil) :: String.t()
   def normalize_symbol_code(symbol_code) do
     if symbol_code && symbol_code != "", do: symbol_code, else: ">"
   end
@@ -211,6 +229,7 @@ defmodule AprsmeWeb.AprsSymbol do
       iex> AprsmeWeb.AprsSymbol.get_table_id("]")
       "2"
   """
+  @spec get_table_id(String.t()) :: String.t()
   def get_table_id(symbol_table) do
     case symbol_table do
       # Primary table
@@ -233,6 +252,7 @@ defmodule AprsmeWeb.AprsSymbol do
       iex> AprsmeWeb.AprsSymbol.render_marker_html("/", "_", "W1AW")
       "<div style=\"position: relative; width: 32px; height: 32px; display: flex; align-items: center;\">..."
   """
+  @spec render_marker_html(String.t() | nil, String.t() | nil, String.t() | nil, integer()) :: String.t()
   def render_marker_html(symbol_table, symbol_code, callsign \\ nil, size \\ 32) do
     # For symbols without callsigns, use Cachex for better caching
     if is_nil(callsign) do
@@ -254,6 +274,7 @@ defmodule AprsmeWeb.AprsSymbol do
     end
   end
 
+  @spec generate_marker_html(String.t() | nil, String.t() | nil, String.t() | nil, integer()) :: String.t()
   defp generate_marker_html(symbol_table, symbol_code, callsign, size) do
     sprite_info = get_sprite_info(symbol_table, symbol_code)
 
@@ -330,6 +351,7 @@ defmodule AprsmeWeb.AprsSymbol do
       iex> AprsmeWeb.AprsSymbol.render_style("/", "_", 32)
       "width: 32px; height: 32px; background-image: url(/aprs-symbols/aprs-symbols-128-0@2x.png); ..."
   """
+  @spec render_style(String.t() | nil, String.t() | nil, integer()) :: String.t()
   def render_style(symbol_table, symbol_code, size \\ 32) do
     sprite_info = get_sprite_info(symbol_table, symbol_code)
 
@@ -347,6 +369,7 @@ defmodule AprsmeWeb.AprsSymbol do
       iex> AprsmeWeb.AprsSymbol.extract_from_packet(%{})
       {"/", ">"}
   """
+  @spec extract_from_packet(map()) :: {String.t(), String.t()}
   def extract_from_packet(packet) do
     symbol_table_id = get_packet_field(packet, :symbol_table_id, "/")
     symbol_code = get_packet_field(packet, :symbol_code, ">")
@@ -355,6 +378,7 @@ defmodule AprsmeWeb.AprsSymbol do
   end
 
   # Helper function to safely extract a value from a packet or data_extended map
+  @spec get_packet_field(map(), atom(), any()) :: any()
   defp get_packet_field(packet, field, default) do
     data_extended = Map.get(packet, :data_extended, Map.get(packet, "data_extended", %{})) || %{}
 
diff --git a/lib/aprsme_web/live/weather_live/callsign_view.ex b/lib/aprsme_web/live/weather_live/callsign_view.ex
index 0b46a0a..299033f 100644
--- a/lib/aprsme_web/live/weather_live/callsign_view.ex
+++ b/lib/aprsme_web/live/weather_live/callsign_view.ex
@@ -232,9 +232,9 @@ defmodule AprsmeWeb.WeatherLive.CallsignView do
     value = PacketUtils.get_weather_field(packet, field)
 
     case value do
-      nil -> false
       "N/A" -> false
       "" -> false
+      nil -> false
       _ -> true
     end
   end
@@ -246,13 +246,13 @@ defmodule AprsmeWeb.WeatherLive.CallsignView do
     value = PacketUtils.get_weather_field(packet, key)
 
     case value do
-      nil ->
-        nil
-
       "N/A" ->
         nil
 
-      value when is_number(value) ->
+      nil ->
+        nil
+
+      value when is_binary(value) ->
         case @weather_formatters[key] do
           {formatter, separator} ->
             {converted_value, unit} = formatter.(value, locale)
@@ -262,7 +262,6 @@ defmodule AprsmeWeb.WeatherLive.CallsignView do
             "#{value}"
         end
 
-      value when is_binary(value) ->
         case @weather_formatters[key] do
           {formatter, separator} ->
             case Float.parse(value) do
@@ -278,8 +277,15 @@ defmodule AprsmeWeb.WeatherLive.CallsignView do
             "#{value}"
         end
 
-      _ ->
-        nil
+      value when is_number(value) ->
+        case @weather_formatters[key] do
+          {formatter, separator} ->
+            {converted_value, unit} = formatter.(value, locale)
+            "#{converted_value}#{separator}#{unit}"
+
+          nil ->
+            "#{value}"
+        end
     end
   end
 end
diff --git a/lib/aprsme_web/plugs/rate_limiter.ex b/lib/aprsme_web/plugs/rate_limiter.ex
index 1f175a2..23d30b3 100644
--- a/lib/aprsme_web/plugs/rate_limiter.ex
+++ b/lib/aprsme_web/plugs/rate_limiter.ex
@@ -5,6 +5,15 @@ defmodule AprsmeWeb.Plugs.RateLimiter do
   import Phoenix.Controller
   import Plug.Conn
 
+  @type key_type :: :ip | :user_agent | (Plug.Conn.t() -> String.t()) | String.t()
+  @type init_opts :: [
+          scale: integer(),
+          limit: integer(),
+          key: key_type(),
+          error_message: String.t()
+        ]
+
+  @spec init(Keyword.t()) :: init_opts()
   def init(opts) do
     # Default options
     Keyword.merge(
@@ -21,6 +30,7 @@ defmodule AprsmeWeb.Plugs.RateLimiter do
     )
   end
 
+  @spec call(Plug.Conn.t(), init_opts()) :: Plug.Conn.t()
   def call(conn, opts) do
     key = get_key(conn, opts[:key])
     scale = opts[:scale]
@@ -39,6 +49,7 @@ defmodule AprsmeWeb.Plugs.RateLimiter do
     end
   end
 
+  @spec get_key(Plug.Conn.t(), key_type()) :: String.t()
   defp get_key(conn, :ip) do
     # Check headers in order of preference
     case {get_req_header(conn, "cf-connecting-ip"), get_req_header(conn, "x-forwarded-for"),
diff --git a/lib/aprsme_web/time_helpers.ex b/lib/aprsme_web/time_helpers.ex
index 960a9e5..0e95f78 100644
--- a/lib/aprsme_web/time_helpers.ex
+++ b/lib/aprsme_web/time_helpers.ex
@@ -23,6 +23,7 @@ defmodule AprsmeWeb.TimeHelpers do
     format_time_diff(diff_seconds) <> " " <> gettext("ago")
   end
 
+  @spec format_time_diff(integer()) :: String.t()
   defp format_time_diff(seconds) when seconds < 60, do: gettext("less than a minute")
   defp format_time_diff(seconds) when seconds < 120, do: gettext("1 minute")
   defp format_time_diff(seconds) when seconds < 3600, do: gettext("%{count} minutes", count: div(seconds, 60))
diff --git a/lib/aprsme_web/time_utils.ex b/lib/aprsme_web/time_utils.ex
index ae2ddd9..0f41be0 100644
--- a/lib/aprsme_web/time_utils.ex
+++ b/lib/aprsme_web/time_utils.ex
@@ -6,6 +6,7 @@ defmodule AprsmeWeb.TimeUtils do
   @doc """
   Returns a DateTime that is the specified number of hours before now.
   """
+  @spec hours_ago(number()) :: DateTime.t()
   def hours_ago(hours) when is_number(hours) do
     DateTime.add(DateTime.utc_now(), -hours * 3600, :second)
   end
@@ -13,33 +14,41 @@ defmodule AprsmeWeb.TimeUtils do
   @doc """
   Returns a DateTime that is one hour before now.
   """
+  @spec one_hour_ago() :: DateTime.t()
   def one_hour_ago, do: hours_ago(1)
 
   @doc """
   Returns a DateTime that is 24 hours (one day) before now.
   """
+  @spec one_day_ago() :: DateTime.t()
   def one_day_ago, do: hours_ago(24)
 
   @doc """
   Returns a DateTime that is 48 hours (two days) before now.
   """
+  @spec two_days_ago() :: DateTime.t()
   def two_days_ago, do: hours_ago(48)
 
   @doc """
   Returns a DateTime that is 7 days (one week) before now.
   """
+  @spec one_week_ago() :: DateTime.t()
   def one_week_ago, do: hours_ago(24 * 7)
 
   @doc """
   Returns a DateTime that is the specified number of days before now.
   """
+  @spec days_ago(number()) :: DateTime.t()
   def days_ago(days) when is_number(days) do
     DateTime.add(DateTime.utc_now(), -days, :day)
   end
 
+  @type time_range_atom :: :last_hour | :last_day | :last_two_days | :last_week
+
   @doc """
   Returns a tuple of {start_time, end_time} for common time ranges.
   """
+  @spec time_range(time_range_atom()) :: {DateTime.t(), DateTime.t()}
   def time_range(:last_hour), do: {one_hour_ago(), DateTime.utc_now()}
   def time_range(:last_day), do: {one_day_ago(), DateTime.utc_now()}
   def time_range(:last_two_days), do: {two_days_ago(), DateTime.utc_now()}
@@ -48,5 +57,6 @@ defmodule AprsmeWeb.TimeUtils do
   @doc """
   Returns a default time range of 48 hours.
   """
+  @spec default_time_range() :: {DateTime.t(), DateTime.t()}
   def default_time_range, do: time_range(:last_two_days)
 end
diff --git a/lib/aprsme_web/user_auth.ex b/lib/aprsme_web/user_auth.ex
index a224f56..208cc9a 100644
--- a/lib/aprsme_web/user_auth.ex
+++ b/lib/aprsme_web/user_auth.ex
@@ -40,6 +40,7 @@ defmodule AprsmeWeb.UserAuth do
     |> redirect(to: user_return_to || signed_in_path(conn))
   end
 
+  @spec maybe_write_remember_me_cookie(Plug.Conn.t(), String.t(), map()) :: Plug.Conn.t()
   defp maybe_write_remember_me_cookie(conn, token, %{"remember_me" => "true"}) do
     put_resp_cookie(conn, @remember_me_cookie, token, @remember_me_options)
   end
@@ -61,6 +62,7 @@ defmodule AprsmeWeb.UserAuth do
   #       |> put_session(:preferred_locale, preferred_locale)
   #     end
   #
+  @spec renew_session(Plug.Conn.t()) :: Plug.Conn.t()
   defp renew_session(conn) do
     conn
     |> configure_session(renew: true)
@@ -98,6 +100,7 @@ defmodule AprsmeWeb.UserAuth do
     assign(conn, :current_user, user)
   end
 
+  @spec ensure_user_token(Plug.Conn.t()) :: {String.t() | nil, Plug.Conn.t()}
   defp ensure_user_token(conn) do
     case get_session(conn, :user_token) do
       nil -> ensure_user_token_from_cookie(conn)
@@ -105,6 +108,7 @@ defmodule AprsmeWeb.UserAuth do
     end
   end
 
+  @spec ensure_user_token_from_cookie(Plug.Conn.t()) :: {String.t() | nil, Plug.Conn.t()}
   defp ensure_user_token_from_cookie(conn) do
     conn = fetch_cookies(conn, signed: [@remember_me_cookie])
 
@@ -180,6 +184,7 @@ defmodule AprsmeWeb.UserAuth do
     end
   end
 
+  @spec mount_current_user(map(), Socket.t()) :: Socket.t()
   defp mount_current_user(session, socket) do
     case session do
       %{"user_token" => user_token} ->
@@ -229,17 +234,20 @@ defmodule AprsmeWeb.UserAuth do
     end
   end
 
+  @spec put_token_in_session(Plug.Conn.t(), String.t()) :: Plug.Conn.t()
   defp put_token_in_session(conn, token) do
     conn
     |> put_session(:user_token, token)
     |> put_session(:live_socket_id, "users_sessions:#{Base.url_encode64(token)}")
   end
 
+  @spec maybe_store_return_to(Plug.Conn.t()) :: Plug.Conn.t()
   defp maybe_store_return_to(%{method: "GET"} = conn) do
     put_session(conn, :user_return_to, current_path(conn))
   end
 
   defp maybe_store_return_to(conn), do: conn
 
+  @spec signed_in_path(Plug.Conn.t() | Socket.t()) :: String.t()
   defp signed_in_path(_conn), do: ~p"/"
 end