diff --git a/etherlink/bin_floodgate/craft.ml b/etherlink/bin_floodgate/craft.ml
index 196bdeca5c27645e6c790ca8a00b48f48f5fd00f..3e8d366aafba003bb44af1ff8c3b6eb597e85193 100644
--- a/etherlink/bin_floodgate/craft.ml
+++ b/etherlink/bin_floodgate/craft.ml
@@ -34,7 +34,7 @@ let prepare_and_forge_tx ?to_ ?data ~gas_limit ~base_fee_per_gas ~chain_id
 
 let transfer ?nonce ?to_ ?data ~value ~gas_limit ~infos ~from () =
   let nonce = Option.value nonce ~default:from.Account.nonce |> Z.to_int in
-  let (Ethereum_types.Qty chain_id) = infos.Network_info.chain_id in
+  let (Ethereum_types.Chain_id chain_id) = infos.Network_info.chain_id in
   let txn =
     prepare_and_forge_tx
       ?to_
diff --git a/etherlink/bin_floodgate/dune b/etherlink/bin_floodgate/dune
index aa562c93030fffe0dcd6f2bef1041c39970f2ccc..260775957c6c2e2c95236518227470d41749c702 100644
--- a/etherlink/bin_floodgate/dune
+++ b/etherlink/bin_floodgate/dune
@@ -16,6 +16,7 @@
   octez-libs.clic
   octez-evm-node-libs.evm_node_lib_dev
   octez-evm-node-libs.evm_node_lib_dev_encoding
+  octez-evm-node-libs.evm_node_config
   octez-libs.tezos-workers)
  (link_flags
   (:standard)
@@ -24,4 +25,5 @@
   (:standard)
   -open Tezos_base.TzPervasives
   -open Evm_node_lib_dev
-  -open Evm_node_lib_dev_encoding))
+  -open Evm_node_lib_dev_encoding
+  -open Evm_node_config))
diff --git a/etherlink/bin_floodgate/floodgate_events.ml b/etherlink/bin_floodgate/floodgate_events.ml
index 55c8a06a34dd725747c1fdcb5ab7a3921f02cf36..af09740786dd9e2a61fa865a4698e41e4d209226 100644
--- a/etherlink/bin_floodgate/floodgate_events.ml
+++ b/etherlink/bin_floodgate/floodgate_events.ml
@@ -28,7 +28,7 @@ let is_ready =
        {base_fee_per_gas})"
     ~level:Notice
     ~pp2:pp_eth
-    ("chain_id", Ethereum_types.quantity_encoding)
+    ("chain_id", Ethereum_types.Chain_id.encoding)
     ("base_fee_per_gas", Data_encoding.n)
 
 let tx_queue_is_ready =
diff --git a/etherlink/bin_floodgate/floodgate_events.mli b/etherlink/bin_floodgate/floodgate_events.mli
index d549431db907cddc7e94b56c0704530a7fb210f1..97bec6f33e0563b81d8e1c30024a6917a18b4b35 100644
--- a/etherlink/bin_floodgate/floodgate_events.mli
+++ b/etherlink/bin_floodgate/floodgate_events.mli
@@ -8,7 +8,7 @@
 
 (** [is_ready chain_id base_fee_per_gas] advertises that Floodgate has started
     and is ready to spam. *)
-val is_ready : Ethereum_types.quantity -> Z.t -> unit Lwt.t
+val is_ready : Ethereum_types.chain_id -> Z.t -> unit Lwt.t
 
 (** [tx_queue_is_ready ()] advertises that the [Tx_queue] is ready to receive
     transactions. *)
@@ -48,11 +48,11 @@ val reimbursed_controller : Account.t -> unit Lwt.t
     has been funded and is now used to spam the Etherlink network. *)
 val setup_completed : unit -> unit Lwt.t
 
-(** [injecting_transactions nb] advertises [nb] transactions are about to be 
+(** [injecting_transactions nb] advertises [nb] transactions are about to be
     injected to the relay endpoint with a batch of [eth_sendRawTransaction]. *)
 val injecting_transactions : int -> unit Lwt.t
 
-(** [deploy_erc20 address] advertises an ERC20 contract as been deployed at 
+(** [deploy_erc20 address] advertises an ERC20 contract as been deployed at
     address [address]. *)
 val deploy_erc20 : string -> unit Lwt.t
 
diff --git a/etherlink/bin_floodgate/network_info.ml b/etherlink/bin_floodgate/network_info.ml
index 334c4c78862cb09c8fcd01db3f21178fe4b2c269..728004ad16fa654e48bba6446b280204c825b20c 100644
--- a/etherlink/bin_floodgate/network_info.ml
+++ b/etherlink/bin_floodgate/network_info.ml
@@ -6,7 +6,7 @@
 (*                                                                           *)
 (*****************************************************************************)
 
-type t = {chain_id : Ethereum_types.quantity; base_fee_per_gas : Z.t}
+type t = {chain_id : Ethereum_types.chain_id; base_fee_per_gas : Z.t}
 
 let get_chain_id ~evm_node_endpoint =
   let open Lwt_result_syntax in
@@ -17,8 +17,9 @@ let get_chain_id ~evm_node_endpoint =
       ~evm_node_endpoint
       ()
   in
+  let mainnet_chain_id = Configuration.chain_id Mainnet in
   let* () =
-    when_ (chain_id = Constants.chain_id Mainnet) @@ fun () ->
+    when_ (chain_id = mainnet_chain_id) @@ fun () ->
     Lwt_result.ok (Floodgate_events.mainnet_experiment ())
   in
   return chain_id
diff --git a/etherlink/bin_floodgate/network_info.mli b/etherlink/bin_floodgate/network_info.mli
index 3c3e7e7cab50f75bb052835157975d5b87ea4fdc..87c921633fc234e1fe61208da490d194ff495503 100644
--- a/etherlink/bin_floodgate/network_info.mli
+++ b/etherlink/bin_floodgate/network_info.mli
@@ -6,7 +6,7 @@
 (*                                                                           *)
 (*****************************************************************************)
 
-type t = {chain_id : Ethereum_types.quantity; base_fee_per_gas : Z.t}
+type t = {chain_id : Ethereum_types.chain_id; base_fee_per_gas : Z.t}
 
 val fetch : rpc_endpoint:Uri.t -> base_fee_factor:float -> t tzresult Lwt.t
 
diff --git a/etherlink/bin_node/config/configuration.ml b/etherlink/bin_node/config/configuration.ml
index 8303988938cf7cf8c0f80212b6a07c4f2f0391ed..718e482e4e21ac7470ef9c169582287e9abfec0b 100644
--- a/etherlink/bin_node/config/configuration.ml
+++ b/etherlink/bin_node/config/configuration.ml
@@ -57,6 +57,11 @@ let chain_id network =
   Ethereum_types.Chain_id
     (Z.of_int (match network with Mainnet -> 0xa729 | Testnet -> 0x1f47b))
 
+let chain_id_encoding : Ethereum_types.chain_id Data_encoding.t =
+  let open Ethereum_types in
+  let open Data_encoding in
+  conv (fun (Chain_id z) -> z) (fun z -> Chain_id z) z
+
 type l2_chain = {chain_id : Ethereum_types.chain_id}
 
 type experimental_features = {
@@ -822,13 +827,9 @@ let opt_monitor_websocket_heartbeat_encoding =
 
 let l2_chain_encoding : l2_chain Data_encoding.t =
   let open Data_encoding in
-  let open Evm_node_lib_dev_encoding in
   conv (fun {chain_id} -> chain_id) (fun chain_id -> {chain_id})
   @@ obj1
-       (req
-          "chain_id"
-          ~description:"The id of the l2 chain"
-          Ethereum_types.chain_id_encoding)
+       (req "chain_id" ~description:"The id of the l2 chain" chain_id_encoding)
 
 let experimental_features_encoding =
   let open Data_encoding in
diff --git a/etherlink/bin_node/lib_dev/constants.ml b/etherlink/bin_node/lib_dev/constants.ml
index c8021c0012419ccb8bdf9755e0cd9a010dfd39c3..000b2321e4870fd494935ece3e0dcac106cc4c58 100644
--- a/etherlink/bin_node/lib_dev/constants.ml
+++ b/etherlink/bin_node/lib_dev/constants.ml
@@ -11,9 +11,6 @@ let network_name = function
   | Configuration.Mainnet -> "Mainnet"
   | Testnet -> "Testnet"
 
-let chain_id network =
-  match Configuration.chain_id network with Chain_id x -> Ethereum_types.Qty x
-
 let rollup_address network =
   Tezos_crypto.Hashed.Smart_rollup_address.of_b58check_exn
   @@
diff --git a/etherlink/bin_node/lib_dev/constants.mli b/etherlink/bin_node/lib_dev/constants.mli
index 9482f7d3be7d05958c3afe7f8dc1f22a35d7b651..b213e334d5737b2745be6413b143d9b5ce1f436f 100644
--- a/etherlink/bin_node/lib_dev/constants.mli
+++ b/etherlink/bin_node/lib_dev/constants.mli
@@ -14,6 +14,4 @@ val network_name : Configuration.supported_network -> string
 val rollup_address :
   Configuration.supported_network -> Tezos_crypto.Hashed.Smart_rollup_address.t
 
-val chain_id : Configuration.supported_network -> Ethereum_types.quantity
-
 val latest_snapshot_url : Configuration.supported_network -> string
diff --git a/etherlink/bin_node/lib_dev/durable_storage.ml b/etherlink/bin_node/lib_dev/durable_storage.ml
index a02cccb365bf42266d46f538c0d539896b312104..99441c94f461dedcbfc697c56bbdd68b1e2d95e5 100644
--- a/etherlink/bin_node/lib_dev/durable_storage.ml
+++ b/etherlink/bin_node/lib_dev/durable_storage.ml
@@ -271,7 +271,10 @@ let block_receipts read n =
   Lwt.return_ok receipts
 
 let chain_id read =
-  inspect_durable_and_decode read Durable_storage_path.chain_id decode_number_le
+  inspect_durable_and_decode
+    read
+    Durable_storage_path.chain_id
+    Chain_id.decode_le
 
 let base_fee_per_gas read =
   let open Lwt_result_syntax in
diff --git a/etherlink/bin_node/lib_dev/encodings/ethereum_types.ml b/etherlink/bin_node/lib_dev/encodings/ethereum_types.ml
index 500e3fa13741d43837e18bf6b6beee61689a259d..6ed70377acf1cd0b9e8a6c1026397817ac81623c 100644
--- a/etherlink/bin_node/lib_dev/encodings/ethereum_types.ml
+++ b/etherlink/bin_node/lib_dev/encodings/ethereum_types.ml
@@ -115,11 +115,29 @@ let quantity_encoding =
 
 let pp_quantity fmt (Qty q) = Z.pp_print fmt q
 
-type chain_id = Chain_id of Z.t
+let decode_z_le bytes = Bytes.to_string bytes |> Z.of_bits
 
-let chain_id_encoding : chain_id Data_encoding.t =
-  let open Data_encoding in
-  conv (fun (Chain_id z) -> z) (fun z -> Chain_id z) z
+let decode_z_be bytes =
+  Bytes.fold_left
+    (fun acc c ->
+      let open Z in
+      add (of_int (Char.code c)) (shift_left acc 8))
+    Z.zero
+    bytes
+
+type chain_id = Chain_id of Z.t [@@ocaml.unboxed]
+
+module Chain_id = struct
+  let encoding =
+    Data_encoding.conv
+      (fun (Chain_id c) -> z_to_hexa c)
+      (fun c -> Chain_id (Z.of_string c))
+      Data_encoding.string
+
+  let decode_le bytes = Chain_id (decode_z_le bytes)
+
+  let decode_be bytes = Chain_id (decode_z_be bytes)
+end
 
 type block_hash = Block_hash of hex [@@ocaml.unboxed]
 
@@ -254,16 +272,9 @@ let decode_address bytes = Address (decode_hex bytes)
 
 let encode_address (Address address) = encode_hex address
 
-let decode_number_le bytes = Bytes.to_string bytes |> Z.of_bits |> quantity_of_z
+let decode_number_le bytes = decode_z_le bytes |> quantity_of_z
 
-let decode_number_be bytes =
-  Bytes.fold_left
-    (fun acc c ->
-      let open Z in
-      add (of_int (Char.code c)) (shift_left acc 8))
-    Z.zero
-    bytes
-  |> quantity_of_z
+let decode_number_be bytes = decode_z_be bytes |> quantity_of_z
 
 let decode_hash bytes = Hash (decode_hex bytes)
 
diff --git a/etherlink/bin_node/lib_dev/encodings/ethereum_types.mli b/etherlink/bin_node/lib_dev/encodings/ethereum_types.mli
index efaf47b67b9c3355c178732d0970fa5a6eefebd1..ed79c265fed2831b651784386e80bc3a04551d6f 100644
--- a/etherlink/bin_node/lib_dev/encodings/ethereum_types.mli
+++ b/etherlink/bin_node/lib_dev/encodings/ethereum_types.mli
@@ -53,9 +53,15 @@ val hex_of_utf8 : string -> hex
 (** [hex_of_bytes] transforms the [bytes] to hexadecimal. *)
 val hex_of_bytes : bytes -> hex
 
-type chain_id = Chain_id of Z.t
+type chain_id = Chain_id of Z.t [@@unboxed]
 
-val chain_id_encoding : chain_id Data_encoding.t
+module Chain_id : sig
+  val encoding : chain_id Data_encoding.t
+
+  val decode_le : bytes -> chain_id
+
+  val decode_be : bytes -> chain_id
+end
 
 (** Ethereum block hash (32 bytes) *)
 type block_hash = Block_hash of hex [@@unboxed]
diff --git a/etherlink/bin_node/lib_dev/encodings/transaction.ml b/etherlink/bin_node/lib_dev/encodings/transaction.ml
index f6b1951d272fe62ed37ddc859c7952e821f0d252..9f0e3102072984bc6a3c8f477c3a228b94ec9c65 100644
--- a/etherlink/bin_node/lib_dev/encodings/transaction.ml
+++ b/etherlink/bin_node/lib_dev/encodings/transaction.ml
@@ -93,7 +93,7 @@ let decode_transaction ?chain_id ~tx_type ~nonce ~max_priority_fee_per_gas
         else if v = of_int 27 || v = of_int 28 then return None
         else fail "Chain ID cannot be decoded"
     | Some chain_id ->
-        let (Qty chain_id) = decode_number_be chain_id in
+        let (Chain_id chain_id) = Chain_id.decode_be chain_id in
         return (Some chain_id)
   in
   return
diff --git a/etherlink/bin_node/lib_dev/evm_ro_context.ml b/etherlink/bin_node/lib_dev/evm_ro_context.ml
index a88fb2ae1a36d313a6e79511cf131b59f6b262fd..edd72db7012b88150ac3f7a73909d601d7f8bec6 100644
--- a/etherlink/bin_node/lib_dev/evm_ro_context.ml
+++ b/etherlink/bin_node/lib_dev/evm_ro_context.ml
@@ -32,7 +32,7 @@ let read state path =
 let network_sanity_check ~network ctxt =
   let open Lwt_result_syntax in
   let expected_smart_rollup_address = Constants.rollup_address network in
-  let (Qty expected_chain_id) = Constants.chain_id network in
+  let (Chain_id expected_chain_id) = Configuration.chain_id network in
 
   let* _, hash = Evm_store.(use ctxt.store Context_hashes.get_latest) in
   let* evm_state = get_evm_state ctxt hash in
@@ -40,7 +40,7 @@ let network_sanity_check ~network ctxt =
 
   let* () =
     match chain_id with
-    | Ok (Qty chain_id) ->
+    | Ok (Chain_id chain_id) ->
         unless Compare.Z.(chain_id = expected_chain_id) @@ fun () ->
         failwith
           "Local state is inconsistent with selected network %a: incorrect \
diff --git a/etherlink/bin_node/lib_dev/rpc_encodings.ml b/etherlink/bin_node/lib_dev/rpc_encodings.ml
index 135f73e6b5701489aec250eb15ce79b34906d3c8..fd8d0f6c1f6834d8438b642ebe40c9bae14b15e1 100644
--- a/etherlink/bin_node/lib_dev/rpc_encodings.ml
+++ b/etherlink/bin_node/lib_dev/rpc_encodings.ml
@@ -224,11 +224,11 @@ end
 module Chain_id = struct
   type input = unit
 
-  type output = Ethereum_types.quantity
+  type output = Ethereum_types.chain_id
 
   let input_encoding = Data_encoding.unit
 
-  let output_encoding = Ethereum_types.quantity_encoding
+  let output_encoding = Ethereum_types.Chain_id.encoding
 
   let method_ = "eth_chainId"
 
diff --git a/etherlink/bin_node/lib_dev/rpc_encodings.mli b/etherlink/bin_node/lib_dev/rpc_encodings.mli
index d1679a2b137491825b0f4167214c573498d32fc8..2d776e218671f77bf2c6561eab481c92a48c5390 100644
--- a/etherlink/bin_node/lib_dev/rpc_encodings.mli
+++ b/etherlink/bin_node/lib_dev/rpc_encodings.mli
@@ -137,7 +137,7 @@ module Kernel_root_hash :
 module Network_id : METHOD with type input = unit and type output = string
 
 module Chain_id :
-  METHOD with type input = unit and type output = Ethereum_types.quantity
+  METHOD with type input = unit and type output = Ethereum_types.chain_id
 
 module Accounts :
   METHOD with type input = unit and type output = Ethereum_types.address list
diff --git a/etherlink/bin_node/lib_dev/services.ml b/etherlink/bin_node/lib_dev/services.ml
index 534e490aa54b3e185c6b5b809c6a8ff3c8ace8ea..0306337638dbdcc8484561c6436619c7e88490e7 100644
--- a/etherlink/bin_node/lib_dev/services.ml
+++ b/etherlink/bin_node/lib_dev/services.ml
@@ -442,11 +442,11 @@ let dispatch_request (rpc : Configuration.rpc) (config : Configuration.t)
         | Network_id.Method ->
             let f (_ : unit option) =
               let open Lwt_result_syntax in
-              let* (Qty chain_id) = Backend_rpc.chain_id () in
+              let* (Chain_id chain_id) = Backend_rpc.chain_id () in
               rpc_ok (Z.to_string chain_id)
             in
             build ~f module_ parameters
-        | Chain_id.Method ->
+        | Rpc_encodings.Chain_id.Method ->
             let f (_ : unit option) =
               let* chain_id = Backend_rpc.chain_id () in
               rpc_ok chain_id
diff --git a/etherlink/bin_node/lib_dev/services_backend_sig.ml b/etherlink/bin_node/lib_dev/services_backend_sig.ml
index e70800767e17cd67f1575d2a4387b7bddcffe34d..3a5fc3d75d363960b2a974fc2ecaa6ebc56afc00 100644
--- a/etherlink/bin_node/lib_dev/services_backend_sig.ml
+++ b/etherlink/bin_node/lib_dev/services_backend_sig.ml
@@ -46,7 +46,7 @@ module type S = sig
     Ethereum_types.quantity tzresult Lwt.t
 
   (** [chain_id ()] returns chain id defined by the rollup. *)
-  val chain_id : unit -> Ethereum_types.quantity tzresult Lwt.t
+  val chain_id : unit -> Ethereum_types.chain_id tzresult Lwt.t
 
   (** [base_fee_per_gas ()] returns base fee defined by the rollup. *)
   val base_fee_per_gas : unit -> Ethereum_types.quantity tzresult Lwt.t
diff --git a/etherlink/bin_node/lib_dev/validate.ml b/etherlink/bin_node/lib_dev/validate.ml
index 6734e623b0084d6aca3842467ce03897e177ac91..d18009d1a350d536cb2746371c71f35a0c9ce464 100644
--- a/etherlink/bin_node/lib_dev/validate.ml
+++ b/etherlink/bin_node/lib_dev/validate.ml
@@ -24,7 +24,7 @@ let validate_chain_id (module Backend_rpc : Services_backend_sig.S)
   match transaction.chain_id with
   | None -> return (Ok ())
   | Some transaction_chain_id ->
-      let* (Qty chain_id) = Backend_rpc.chain_id () in
+      let* (Chain_id chain_id) = Backend_rpc.chain_id () in
       if Z.equal transaction_chain_id chain_id then return (Ok ())
       else return (Error "Invalid chain id")
 
diff --git a/manifest/product_etherlink.ml b/manifest/product_etherlink.ml
index f61b59277b228e54522613c78398a35f1972ffed..94f7bf2ec1041a5303211b6531600edf24b523fd 100644
--- a/manifest/product_etherlink.ml
+++ b/manifest/product_etherlink.ml
@@ -473,5 +473,6 @@ let _floodgate_bin =
         octez_clic;
         evm_node_lib_dev |> open_;
         evm_node_lib_dev_encoding |> open_;
+        evm_node_config |> open_;
         octez_workers;
       ]