diff --git a/lib/archethic/contracts/contract/state.ex b/lib/archethic/contracts/contract/state.ex
index ebdb9871e..3a6fb9b4f 100644
--- a/lib/archethic/contracts/contract/state.ex
+++ b/lib/archethic/contracts/contract/state.ex
@@ -29,4 +29,39 @@ defmodule Archethic.Contracts.Contract.State do
   """
   @spec deserialize(bitstring()) :: {t(), bitstring()}
   def deserialize(bitsting), do: TypedEncoding.deserialize(bitsting, :compact)
+
+  @doc """
+  Return a valid JSON of the given state
+  Handles the fact that keys can be non-string
+  """
+  @spec to_json(state :: t()) :: map()
+  def to_json(state) do
+    serialize_map_keys(state)
+  end
+
+  @doc """
+  Returns the state as a prettified JSON
+  Handles the fact that keys can be non-string
+  """
+  @spec format(state :: t()) :: String.t()
+  def format(state) do
+    Jason.encode!(to_json(state), pretty: true)
+  end
+
+  defp serialize_map_keys(map) when is_map(map) do
+    map
+    |> Enum.reduce(%{}, fn
+      {k, v}, acc when is_binary(k) ->
+        Map.put(acc, k, serialize_map_keys(v))
+
+      {k, v}, acc ->
+        Map.put(acc, Jason.encode!(k), serialize_map_keys(v))
+    end)
+  end
+
+  defp serialize_map_keys(list) when is_list(list) do
+    Enum.map(list, &serialize_map_keys/1)
+  end
+
+  defp serialize_map_keys(term), do: term
 end
diff --git a/lib/archethic_web/api/graphql/schema/transaction_type.ex b/lib/archethic_web/api/graphql/schema/transaction_type.ex
index aeac57e09..3082b0912 100644
--- a/lib/archethic_web/api/graphql/schema/transaction_type.ex
+++ b/lib/archethic_web/api/graphql/schema/transaction_type.ex
@@ -4,6 +4,7 @@ defmodule ArchethicWeb.API.GraphQL.Schema.TransactionType do
   use Absinthe.Schema.Notation
 
   alias ArchethicWeb.API.GraphQL.Schema.Resolver
+  alias Archethic.Contracts.Contract.State
 
   alias Archethic.TransactionChain.Transaction
 
@@ -209,7 +210,7 @@ defmodule ArchethicWeb.API.GraphQL.Schema.TransactionType do
     [State] represents the smart contract state
   """
   scalar :state do
-    serialize(& &1)
+    serialize(&State.to_json/1)
   end
 
   @desc """
diff --git a/lib/archethic_web/explorer/live/transaction_details_live.ex b/lib/archethic_web/explorer/live/transaction_details_live.ex
index d23daead1..846a70262 100644
--- a/lib/archethic_web/explorer/live/transaction_details_live.ex
+++ b/lib/archethic_web/explorer/live/transaction_details_live.ex
@@ -332,7 +332,7 @@ defmodule ArchethicWeb.Explorer.TransactionDetailsLive do
   end
 
   def print_state(%UnspentOutput{encoded_payload: encoded_state}) do
-    encoded_state |> State.deserialize() |> elem(0) |> inspect(pretty: true)
+    encoded_state |> State.deserialize() |> elem(0) |> State.format()
   end
 
   defp similar?(
diff --git a/test/archethic/contracts/state_test.exs b/test/archethic/contracts/state_test.exs
index ac0cf816c..aaa887d36 100644
--- a/test/archethic/contracts/state_test.exs
+++ b/test/archethic/contracts/state_test.exs
@@ -14,6 +14,14 @@ defmodule Archethic.Contracts.Contract.StateTest do
     end
   end
 
+  describe "format/1" do
+    test "should return a valid JSON prettified" do
+      state = complex_state()
+
+      assert {:ok, _} = State.format(state) |> Jason.decode()
+    end
+  end
+
   defp complex_state() do
     %{
       "foo" => "bar",