diff --git a/beacon_chain/el/el_manager.nim b/beacon_chain/el/el_manager.nim
index 3bb4978d4..9821d8b0d 100644
--- a/beacon_chain/el/el_manager.nim
+++ b/beacon_chain/el/el_manager.nim
@@ -12,7 +12,7 @@ import
   # Nimble packages:
   chronos, metrics, chronicles/timings,
   json_rpc/[client, errors],
-  web3, web3/ethhexstrings, web3/engine_api,
+  web3, web3/[engine_api, primitives, conversions],
   eth/common/[eth_types, transaction],
   eth/async_utils, stew/[assign2, byteutils, objects, results, shims/hashes, endians2],
   # Local modules:
@@ -1440,10 +1440,11 @@ proc exchangeTransitionConfiguration*(m: ELManager) {.async.} =
   if cancelled == requests.len:
     warn "Failed to exchange configuration with the configured EL end-points"
 
-template readJsonField(j: JsonNode, fieldName: string, ValueType: type): untyped =
-  var res: ValueType
-  fromJson(j[fieldName], fieldName, res)
-  res
+template readJsonField(logEvent, field: untyped, ValueType: type): untyped =
+  if logEvent.field.isNone:
+    raise newException(CatchableError,
+      "Web3 provider didn't return needed logEvent field " & astToStr(field))
+  logEvent.field.get
 
 template init[N: static int](T: type DynamicBytes[N, N]): T =
   T newSeq[byte](N)
@@ -1460,19 +1461,15 @@ proc fetchTimestamp(connection: ELConnection,
 
   blk.timestamp = Eth1BlockTimestamp web3block.timestamp
 
-func depositEventsToBlocks(depositsList: JsonNode): seq[Eth1Block] {.
+func depositEventsToBlocks(depositsList: openArray[JsonString]): seq[Eth1Block] {.
     raises: [CatchableError].} =
-  if depositsList.kind != JArray:
-    raise newException(CatchableError,
-      "Web3 provider didn't return a list of deposit events")
-
   var lastEth1Block: Eth1Block
 
-  for logEvent in depositsList:
+  for logEventData in depositsList:
     let
-      blockNumber = Eth1BlockNumber readJsonField(logEvent, "blockNumber", Quantity)
-      blockHash = readJsonField(logEvent, "blockHash", BlockHash)
-      logData = hexToSeqByte(logEvent["data"].getStr)
+      logEvent = JrpcConv.decode(logEventData.string, LogObject)
+      blockNumber = Eth1BlockNumber readJsonField(logEvent, blockNumber, Quantity)
+      blockHash = readJsonField(logEvent, blockHash, BlockHash)
 
     if lastEth1Block == nil or lastEth1Block.number != blockNumber:
       lastEth1Block = Eth1Block(
@@ -1493,11 +1490,11 @@ func depositEventsToBlocks(depositsList: JsonNode): seq[Eth1Block] {.
       index = init Int64LeBytes
 
     var offset = 0
-    offset += decode(logData, 0, offset, pubkey)
-    offset += decode(logData, 0, offset, withdrawalCredentials)
-    offset += decode(logData, 0, offset, amount)
-    offset += decode(logData, 0, offset, signature)
-    offset += decode(logData, 0, offset, index)
+    offset += decode(logEvent.data, 0, offset, pubkey)
+    offset += decode(logEvent.data, 0, offset, withdrawalCredentials)
+    offset += decode(logEvent.data, 0, offset, amount)
+    offset += decode(logEvent.data, 0, offset, signature)
+    offset += decode(logEvent.data, 0, offset, index)
 
     if pubkey.len != 48 or
        withdrawalCredentials.len != 32 or
@@ -1906,7 +1903,7 @@ proc syncBlockRange(m: ELManager,
   var currentBlock = fromBlock
   while currentBlock <= toBlock:
     var
-      depositLogs: JsonNode = nil
+      depositLogs: seq[JsonString]
       maxBlockNumberRequested: Eth1BlockNumber
       backoff = 100
 
diff --git a/beacon_chain/libnimbus_lc/libnimbus_lc.nim b/beacon_chain/libnimbus_lc/libnimbus_lc.nim
index f3815d2d6..79ec70bfa 100644
--- a/beacon_chain/libnimbus_lc/libnimbus_lc.nim
+++ b/beacon_chain/libnimbus_lc/libnimbus_lc.nim
@@ -1209,15 +1209,12 @@ proc ETHExecutionBlockHeaderCreateFromJson(
   ##
   ## See:
   ## * https://ethereum.org/en/developers/docs/apis/json-rpc/#eth_getblockbyhash
-  let node =
-    try:
-      parseJson($blockHeaderJson)
-    except Exception:
-      return nil
-  var data: BlockObject
-  try:
-    fromJson(node, argName = "", data)
-  except KeyError, ValueError:
+  let data = try:
+    # a direct parameter like JrpcConv.decode($blockHeaderJson, BlockObject)
+    # will cause premature garbage collector kick in.
+    let jsonBytes = $blockHeaderJson
+    JrpcConv.decode(jsonBytes, BlockObject)
+  except SerializationError:
     return nil
   if data == nil:
     return nil
@@ -1445,15 +1442,12 @@ proc ETHTransactionsCreateFromJson(
   ##
   ## See:
   ## * https://ethereum.org/en/developers/docs/apis/json-rpc/#eth_getblockbyhash
-  let node =
-    try:
-      parseJson($transactionsJson)
-    except Exception:
-      return nil
-  var datas: seq[TransactionObject]
-  try:
-    fromJson(node, argName = "", datas)
-  except KeyError, ValueError:
+  var datas = try:
+    # a direct parameter like JrpcConv.decode($transactionsJson, seq[TransactionObject])
+    # will cause premature garbage collector kick in.
+    let jsonBytes = $transactionsJson
+    JrpcConv.decode(jsonBytes, seq[TransactionObject])
+  except SerializationError:
     return nil
 
   var txs = newSeqOfCap[ETHTransaction](datas.len)
@@ -2085,15 +2079,12 @@ proc ETHReceiptsCreateFromJson(
   ##
   ## See:
   ## * https://ethereum.org/en/developers/docs/apis/json-rpc/#eth_gettransactionreceipt
-  let node =
-    try:
-      parseJson($receiptsJson)
-    except Exception:
-      return nil
-  var datas: seq[ReceiptObject]
-  try:
-    fromJson(node, argName = "", datas)
-  except KeyError, ValueError:
+  var datas = try:
+    # a direct parameter like JrpcConv.decode($receiptsJson, seq[ReceiptObject])
+    # will cause premature garbage collector kick in.
+    let jsonBytes = $receiptsJson
+    JrpcConv.decode(jsonBytes, seq[ReceiptObject])
+  except SerializationError:
     return nil
   if datas.len != ETHTransactionsGetCount(transactions):
     return nil
diff --git a/ncli/ncli_testnet.nim b/ncli/ncli_testnet.nim
index 7802eaf2c..766572d43 100644
--- a/ncli/ncli_testnet.nim
+++ b/ncli/ncli_testnet.nim
@@ -443,15 +443,8 @@ proc doCreateTestnet*(config: CliConfig,
       quit 1
 
     try:
-      let blockAsJson = try:
-        parseJson genesisBlockContents.get
-      except CatchableError as err:
-        error "Failed to parse the genesis block json", err = err.msg
-        quit 1
-      except:
-        # TODO The Nim json library should not raise bare exceptions
-        raiseAssert "The Nim json library raise a bare exception"
-      fromJson(blockAsJson, "", genesisBlock)
+      let blockAsJson = genesisBlockContents.get
+      genesisBlock = JrpcConv.decode(blockAsJson, BlockObject)
     except CatchableError as err:
       error "Failed to load the genesis block from json",
             err = err.msg
diff --git a/research/fakeee.nim b/research/fakeee.nim
index 52c955395..dea7e8e30 100644
--- a/research/fakeee.nim
+++ b/research/fakeee.nim
@@ -77,13 +77,13 @@ proc setupEngineAPI*(server: RpcServer) =
       status: PayloadExecutionStatus.syncing))
 
   server.rpc("eth_getBlockByNumber") do(
-      quantityTag: string, fullTransactions: bool) -> JsonNode:
+      quantityTag: string, fullTransactions: bool) -> JsonString:
     info "eth_getBlockByNumber", quantityTag, fullTransactions
 
     return if quantityTag == "latest":
-      %BlockObject(number: 1000.Quantity)
+      JrpcConv.encode(BlockObject(number: 1000.Quantity)).JsonString
     else:
-      newJObject()
+      "{}".JsonString
 
   server.rpc("eth_getBlockByHash") do(
       data: string, fullTransactions: bool) -> BlockObject:
diff --git a/vendor/nim-json-rpc b/vendor/nim-json-rpc
index 08d7fccfe..a6475e49b 160000
--- a/vendor/nim-json-rpc
+++ b/vendor/nim-json-rpc
@@ -1 +1 @@
-Subproject commit 08d7fccfe2025d5a2ecca68e6e7b4dd4a7974a8e
+Subproject commit a6475e49b26d3afc58aaa3d67621c94eafef8efb
diff --git a/vendor/nim-web3 b/vendor/nim-web3
index 45d09b29d..bf1ce869b 160000
--- a/vendor/nim-web3
+++ b/vendor/nim-web3
@@ -1 +1 @@
-Subproject commit 45d09b29d22da63052b259679539a3d4141273a7
+Subproject commit bf1ce869b5f76d9744444b248f6f5c6c782fedc7