diff --git a/cmd/loadtest/loadtest.go b/cmd/loadtest/loadtest.go
index f97935b4..b43cf0e3 100644
--- a/cmd/loadtest/loadtest.go
+++ b/cmd/loadtest/loadtest.go
@@ -1171,7 +1171,6 @@ func loadTestRecall(ctx context.Context, c *ethclient.Client, nonce uint64, orig
 }
 
 func loadTestRPC(ctx context.Context, c *ethclient.Client, nonce uint64, ia *IndexedActivity) (t1 time.Time, t2 time.Time, err error) {
-
 	funcNum := randSrc.Intn(300)
 	t1 = time.Now()
 	defer func() { t2 = time.Now() }()
diff --git a/cmd/rpcfuzz/rpcfuzz.go b/cmd/rpcfuzz/rpcfuzz.go
index d5bc82ae..7d667c5f 100644
--- a/cmd/rpcfuzz/rpcfuzz.go
+++ b/cmd/rpcfuzz/rpcfuzz.go
@@ -134,6 +134,14 @@ const (
 	defaultMaxPriorityFeePerGas = "0x1000000000"
 
 	defaultNonceTestOffset uint64 = 0x100000000
+
+	// JSON-RPC error codes.
+	// https://eips.ethereum.org/EIPS/eip-1474
+	parseErr          = -32700
+	invalidRequestErr = -32600
+	methodNotFoundErr = -32601
+	invalidParamsErr  = -32602
+	internalErr       = -32603
 )
 
 var (
@@ -173,7 +181,6 @@ var (
 
 // setupTests will add all of the `RPCTests` to the `allTests` slice.
 func setupTests(ctx context.Context, rpcClient *rpc.Client) {
-
 	// cast rpc --rpc-url localhost:8545 net_version
 	allTests = append(allTests, &RPCTestGeneric{
 		Name:      "RPCTestNetVersion",
@@ -204,7 +211,7 @@ func setupTests(ctx context.Context, rpcClient *rpc.Client) {
 		Flags:     FlagErrorValidation | FlagStrictValidation,
 		Method:    "web3_sha3",
 		Args:      []interface{}{"68656c6c6f20776f726c64"},
-		Validator: ValidateError(-32602, `cannot unmarshal hex string without 0x prefix`),
+		Validator: ValidateError(invalidParamsErr, `cannot unmarshal hex string without 0x prefix`),
 	})
 
 	// cast rpc --rpc-url localhost:8545 net_listening
@@ -229,7 +236,7 @@ func setupTests(ctx context.Context, rpcClient *rpc.Client) {
 		Flags:     FlagErrorValidation | FlagStrictValidation,
 		Method:    "eth_protocolVersion",
 		Args:      []interface{}{},
-		Validator: ValidateError(-32601, `method eth_protocolVersion does not exist`),
+		Validator: ValidateError(methodNotFoundErr, `method eth_protocolVersion does not exist`),
 	})
 
 	// cast rpc --rpc-url localhost:8545 eth_syncing
@@ -507,7 +514,7 @@ func setupTests(ctx context.Context, rpcClient *rpc.Client) {
 		Name:      "RPCTestEthSignFail",
 		Method:    "eth_sign",
 		Args:      []interface{}{testEthAddress.String(), "0xdeadbeef"},
-		Validator: ValidateError(-32000, `unknown account`),
+		Validator: ValidateError(invalidRequestErr, `unknown account`),
 		Flags:     FlagErrorValidation | FlagStrictValidation | FlagRequiresUnlock,
 	})
 
@@ -529,6 +536,25 @@ func setupTests(ctx context.Context, rpcClient *rpc.Client) {
 		Flags:     FlagRequiresUnlock,
 	})
 
+	// $ curl -X POST -H "Content-Type: application/json" --data '{"jsonrpc":"2.0","method":"eth_sendTransaction","params":[],"id":1}' http://localhost:8545
+	// {"jsonrpc":"2.0","id":1,"error":{"code":-32602,"message":"missing value for required argument 0"}}
+	allTests = append(allTests, &RPCTestGeneric{
+		Name:      "RPCTestEthSendTransactionEmpty",
+		Method:    "eth_sendTransaction",
+		Args:      []interface{}{},
+		Flags:     FlagErrorValidation,
+		Validator: ValidateError(invalidParamsErr, "missing value for required argument 0"),
+	})
+	// $ curl -X POST -H "Content-Type: application/json" --data '{"jsonrpc":"2.0","method":"eth_sendRawTransaction","params":[],"id":1}' http://localhost:8545
+	// {"jsonrpc":"2.0","id":1,"error":{"code":-32602,"message":"missing value for required argument 0"}}
+	allTests = append(allTests, &RPCTestGeneric{
+		Name:      "RPCTestEthSendRawTransactionEmpty",
+		Method:    "eth_sendRawTransaction",
+		Args:      []interface{}{},
+		Flags:     FlagErrorValidation,
+		Validator: ValidateError(invalidParamsErr, "missing value for required argument 0"),
+	})
+
 	// cast rpc --rpc-url localhost:8545 eth_sendRawTransaction '{"from": "0xb9b1cf51a65b50f74ed8bcb258413c02cba2ec57", "to": "0x85dA99c8a7C2C95964c8EfD687E95E632Fc533D6", "data": "0x", "gas": "0x5208", "gasPrice": "0x1", "nonce": "0x1"}'
 	allTests = append(allTests, &RPCTestDynamicArgs{
 		Name:      "RPCTestEthSendRawTransaction",
@@ -540,7 +566,7 @@ func setupTests(ctx context.Context, rpcClient *rpc.Client) {
 		Name:      "RPCTestEthSendRawTransactionNonceTooLow",
 		Method:    "eth_sendRawTransaction",
 		Args:      ArgsSignTransactionWithNonce(ctx, rpcClient, &RPCTestTransactionArgs{To: testEthAddress.String(), Value: "0x123", Gas: "0x5208", Data: "0x", MaxFeePerGas: defaultMaxFeePerGas, MaxPriorityFeePerGas: defaultMaxPriorityFeePerGas}, 0),
-		Validator: ValidateError(-32000, `nonce too low`),
+		Validator: ValidateError(invalidRequestErr, `nonce too low`),
 		Flags:     FlagErrorValidation | FlagStrictValidation,
 	})
 	allTests = append(allTests, &RPCTestDynamicArgs{
@@ -554,14 +580,14 @@ func setupTests(ctx context.Context, rpcClient *rpc.Client) {
 		Name:      "RPCTestEthSendRawTransactionNonceKnown",
 		Method:    "eth_sendRawTransaction",
 		Args:      ArgsSignTransactionWithNonce(ctx, rpcClient, &RPCTestTransactionArgs{To: testEthAddress.String(), Value: "0x123", Gas: "0x5208", Data: "0x", MaxFeePerGas: defaultMaxFeePerGas, MaxPriorityFeePerGas: defaultMaxPriorityFeePerGas}, testAccountNonce|defaultNonceTestOffset),
-		Validator: ValidateError(-32000, `already known`),
+		Validator: ValidateError(invalidRequestErr, `already known`),
 		Flags:     FlagErrorValidation | FlagStrictValidation | FlagOrderDependent,
 	})
 	allTests = append(allTests, &RPCTestDynamicArgs{
 		Name:      "RPCTestEthSendRawTransactionNonceUnderpriced",
 		Method:    "eth_sendRawTransaction",
 		Args:      ArgsSignTransactionWithNonce(ctx, rpcClient, &RPCTestTransactionArgs{To: testEthAddress.String(), Value: "0x1234", Gas: "0x5208", Data: "0x", MaxFeePerGas: defaultMaxFeePerGas, MaxPriorityFeePerGas: defaultMaxPriorityFeePerGas}, testAccountNonce|defaultNonceTestOffset),
-		Validator: ValidateError(-32000, `replacement`),
+		Validator: ValidateError(invalidRequestErr, `replacement`),
 		Flags:     FlagErrorValidation | FlagStrictValidation | FlagOrderDependent,
 	})
 
@@ -610,6 +636,16 @@ func setupTests(ctx context.Context, rpcClient *rpc.Client) {
 		Flags: FlagStrictValidation,
 	})
 
+	// $ curl -X POST -H "Content-Type: application/json" --data '{"jsonrpc": "2.0", "method": "eth_estimateGas", "params": [], "id":1}' localhost:8545
+	// {"jsonrpc":"2.0","id":1,"error":{"code":-32602,"message":"missing value for required argument 0"}}
+	allTests = append(allTests, &RPCTestGeneric{
+		Name:      "RPCTestEthEstimateGasEmpty",
+		Method:    "eth_estimateGas",
+		Args:      []interface{}{},
+		Flags:     FlagErrorValidation,
+		Validator: ValidateError(invalidParamsErr, `missing value for required argument 0`),
+	})
+
 	// cast block --rpc-url localhost:8545 latest
 	allTests = append(allTests, &RPCTestDynamicArgs{
 		Name:   "RPCTestEthGetBlockByHash",
@@ -714,28 +750,28 @@ func setupTests(ctx context.Context, rpcClient *rpc.Client) {
 		Flags:     FlagErrorValidation | FlagStrictValidation,
 		Method:    "eth_getCompilers",
 		Args:      []interface{}{},
-		Validator: ValidateError(-32601, `method eth_getCompilers does not exist`),
+		Validator: ValidateError(methodNotFoundErr, `method eth_getCompilers does not exist`),
 	})
 	allTests = append(allTests, &RPCTestGeneric{
 		Name:      "RPCTestEthCompileSolidity",
 		Flags:     FlagErrorValidation | FlagStrictValidation,
 		Method:    "eth_compileSolidity",
 		Args:      []interface{}{},
-		Validator: ValidateError(-32601, `method eth_compileSolidity does not exist`),
+		Validator: ValidateError(methodNotFoundErr, `method eth_compileSolidity does not exist`),
 	})
 	allTests = append(allTests, &RPCTestGeneric{
 		Name:      "RPCTestEthCompileLLL",
 		Flags:     FlagErrorValidation | FlagStrictValidation,
 		Method:    "eth_compileLLL",
 		Args:      []interface{}{},
-		Validator: ValidateError(-32601, `method eth_compileLLL does not exist`),
+		Validator: ValidateError(methodNotFoundErr, `method eth_compileLLL does not exist`),
 	})
 	allTests = append(allTests, &RPCTestGeneric{
 		Name:      "RPCTestEthCompileSerpent",
 		Flags:     FlagErrorValidation | FlagStrictValidation,
 		Method:    "eth_compileSerpent",
 		Args:      []interface{}{},
-		Validator: ValidateError(-32601, `method eth_compileSerpent does not exist`),
+		Validator: ValidateError(methodNotFoundErr, `method eth_compileSerpent does not exist`),
 	})
 
 	// cast rpc --rpc-url localhost:8545 eth_newFilter "{}"
@@ -859,7 +895,7 @@ func setupTests(ctx context.Context, rpcClient *rpc.Client) {
 		Method:    "eth_getWork",
 		Args:      []interface{}{},
 		Flags:     FlagErrorValidation | FlagStrictValidation,
-		Validator: ValidateError(-32601, `method eth_getWork does not exist`),
+		Validator: ValidateError(methodNotFoundErr, `method eth_getWork does not exist`),
 	})
 	// cast rpc --rpc-url localhost:8545 eth_submitWork 0x0011223344556677 0x00112233445566778899AABBCCDDEEFF 0x00112233445566778899AABBCCDDEEFF
 	allTests = append(allTests, &RPCTestGeneric{
@@ -867,7 +903,7 @@ func setupTests(ctx context.Context, rpcClient *rpc.Client) {
 		Method:    "eth_submitWork",
 		Args:      []interface{}{"0x0011223344556677", "0x00112233445566778899AABBCCDDEEFF", "0x00112233445566778899AABBCCDDEEFF"},
 		Flags:     FlagErrorValidation | FlagStrictValidation,
-		Validator: ValidateError(-32601, `method eth_submitWork does not exist`),
+		Validator: ValidateError(methodNotFoundErr, `method eth_submitWork does not exist`),
 	})
 	// cast rpc --rpc-url localhost:8545 eth_submitHashrate 0x00112233445566778899AABBCCDDEEFF00112233445566778899AABBCCDDEEFF 0x00112233445566778899AABBCCDDEEFF00112233445566778899AABBCCDDEEFF
 	allTests = append(allTests, &RPCTestGeneric{
@@ -875,7 +911,7 @@ func setupTests(ctx context.Context, rpcClient *rpc.Client) {
 		Method:    "eth_submitHashrate",
 		Args:      []interface{}{"0x00112233445566778899AABBCCDDEEFF00112233445566778899AABBCCDDEEFF", "0x00112233445566778899AABBCCDDEEFF00112233445566778899AABBCCDDEEFF"},
 		Flags:     FlagErrorValidation | FlagStrictValidation,
-		Validator: ValidateError(-32601, `method eth_submitHashrate does not exist`),
+		Validator: ValidateError(methodNotFoundErr, `method eth_submitHashrate does not exist`),
 	})
 
 	// cast rpc --rpc-url localhost:8545 eth_feeHistory 128 latest []
@@ -953,7 +989,7 @@ func setupTests(ctx context.Context, rpcClient *rpc.Client) {
 		Method:    "debug_getRawBlock",
 		Args:      []interface{}{"pending"},
 		Flags:     FlagErrorValidation | FlagStrictValidation,
-		Validator: ValidateError(-32000, `not found`),
+		Validator: ValidateError(invalidRequestErr, `not found`),
 	})
 	allTests = append(allTests, &RPCTestGeneric{
 		Name:      "RPCTestDebugGetRawBlockEarliest",
@@ -988,7 +1024,7 @@ func setupTests(ctx context.Context, rpcClient *rpc.Client) {
 		Method:    "debug_getRawHeader",
 		Args:      []interface{}{"pending"},
 		Flags:     FlagErrorValidation | FlagStrictValidation,
-		Validator: ValidateError(-32000, `not found`),
+		Validator: ValidateError(invalidRequestErr, `not found`),
 	})
 	allTests = append(allTests, &RPCTestGeneric{
 		Name:      "RPCTestDebugGetRawHeaderEarliest",
@@ -1050,7 +1086,7 @@ func setupTests(ctx context.Context, rpcClient *rpc.Client) {
 		Method:    "debug_traceBlockByNumber",
 		Args:      []interface{}{"0x0", nil},
 		Flags:     FlagErrorValidation | FlagStrictValidation,
-		Validator: ValidateError(-32000, `genesis is not traceable`),
+		Validator: ValidateError(invalidRequestErr, `genesis is not traceable`),
 	})
 	allTests = append(allTests, &RPCTestGeneric{
 		Name:      "RPCTestDebugTraceBlockByNumberOne",
@@ -1069,7 +1105,7 @@ func setupTests(ctx context.Context, rpcClient *rpc.Client) {
 		Method:    "debug_traceBlockByNumber",
 		Args:      []interface{}{"earliest", nil},
 		Flags:     FlagErrorValidation | FlagStrictValidation,
-		Validator: ValidateError(-32000, `genesis is not traceable`),
+		Validator: ValidateError(invalidRequestErr, `genesis is not traceable`),
 	})
 	allTests = append(allTests, &RPCTestGeneric{
 		Name:      "RPCTestDebugTraceBlockByNumberPending",
@@ -1098,7 +1134,7 @@ func setupTests(ctx context.Context, rpcClient *rpc.Client) {
 		Method:    "debug_traceBlock",
 		Args:      ArgsRawBlock(ctx, rpcClient, "0x0", nil),
 		Flags:     FlagErrorValidation | FlagStrictValidation,
-		Validator: ValidateError(-32000, `genesis is not traceable`),
+		Validator: ValidateError(invalidRequestErr, `genesis is not traceable`),
 	})
 
 	uniqueTests := make(map[RPCTest]struct{})
diff --git a/cmd/rpcfuzz/usage.md b/cmd/rpcfuzz/usage.md
index 7c3e0098..4f118147 100644
--- a/cmd/rpcfuzz/usage.md
+++ b/cmd/rpcfuzz/usage.md
@@ -5,47 +5,71 @@ Some setup might be needed depending on how you're testing. We'll demonstrate wi
 In order to quickly test this, you can run geth in dev mode.
 
 ```bash
-$ geth --dev --dev.period 5 --http --http.addr localhost \
+$ geth \
+    --dev \
+    --dev.period 5 \
+    --http \
+    --http.addr localhost \
     --http.port 8545 \
-    --http.api 'admin,debug,web3,eth,txpool,personal,clique,miner,net' \
-    --verbosity 5 --rpc.gascap 50000000  --rpc.txfeecap 0 \
-    --miner.gaslimit  10 --miner.gasprice 1 --gpo.blocks 1 \
-    --gpo.percentile 1 --gpo.maxprice 10 --gpo.ignoreprice 2 \
+    --http.api 'admin,debug,web3,eth,txpool,personal,miner,net' \
+    --verbosity 5 \
+    --rpc.gascap 50000000 \
+    --rpc.txfeecap 0 \
+    --miner.gaslimit 10 \
+    --miner.gasprice 1 \
+    --gpo.blocks 1 \
+    --gpo.percentile 1 \
+    --gpo.maxprice 10 \
+    --gpo.ignoreprice 2 \
     --dev.gaslimit 50000000
 ```
 
 If we wanted to use erigon for testing, we could do something like this as well.
 
 ```bash
-$ erigon --chain dev --dev.period 5 --http --http.addr localhost \
+$ erigon \
+    --chain dev \
+    --dev.period 5 \
+    --http \
+    --http.addr localhost \
     --http.port 8545 \
-    --http.api 'admin,debug,web3,eth,txpool,personal,clique,miner,net' \
-    --verbosity 5 --rpc.gascap 50000000 \
-    --miner.gaslimit  10 --gpo.blocks 1 \
-    --gpo.percentile 1 --mine
+    --http.api 'admin,debug,web3,eth,txpool,clique,net' \
+    --verbosity 5 \
+    --rpc.gascap 50000000 \
+    --miner.gaslimit 10 \
+    --gpo.blocks 1 \
+    --gpo.percentile 1 \
+    --mine
 ```
 
 Once your Eth client is running and the RPC is functional, you'll need to transfer some amount of ether to a known account that ca be used for testing.
 
 ```
-$ cast send --from "$(cast rpc --rpc-url localhost:8545 eth_coinbase | jq -r '.')" \
-    --rpc-url localhost:8545 --unlocked --value 100ether \
-    0x85dA99c8a7C2C95964c8EfD687E95E632Fc533D6
+$ cast send \
+    --from "$(cast rpc --rpc-url localhost:8545 eth_coinbase | jq -r '.')" \
+    --rpc-url localhost:8545 \
+    --unlocked \
+    --value 100ether \
+    --json \
+    0x85dA99c8a7C2C95964c8EfD687E95E632Fc533D6 | jq
 ```
 
 Then we might want to deploy some test smart contracts. For the purposes of testing we'll our ERC20 contract.
 
 ```bash
-$ cast send --from 0x85dA99c8a7C2C95964c8EfD687E95E632Fc533D6 \
+$ cast send \
+    --from 0x85dA99c8a7C2C95964c8EfD687E95E632Fc533D6 \
     --private-key 0x42b6e34dc21598a807dc19d7784c71b2a7a01f6480dc6f58258f78e539f1a1fa \
-    --rpc-url localhost:8545 --create \
-    "$(cat ./contracts/ERC20.bin)"
+    --rpc-url localhost:8545 \
+    --json \
+    --create \
+    "$(cat ./contracts/tokens/ERC20/ERC20.bin)" | jq
 ```
 
 Once this has been completed this will be the address of the contract: `0x6fda56c57b0acadb96ed5624ac500c0429d59429`.
 
 ```bash
-$  docker run -v $PWD/contracts:/contracts ethereum/solc:stable --storage-layout /contracts/ERC20.sol
+$  docker run -v $PWD/contracts:/contracts ethereum/solc:stable --storage-layout /contracts/tokens/ERC20/ERC20.sol
 ```
 
 ### Links
diff --git a/doc/polycli_rpcfuzz.md b/doc/polycli_rpcfuzz.md
index 3e6cc3fc..62338e09 100644
--- a/doc/polycli_rpcfuzz.md
+++ b/doc/polycli_rpcfuzz.md
@@ -26,47 +26,71 @@ Some setup might be needed depending on how you're testing. We'll demonstrate wi
 In order to quickly test this, you can run geth in dev mode.
 
 ```bash
-$ geth --dev --dev.period 5 --http --http.addr localhost \
+$ geth \
+    --dev \
+    --dev.period 5 \
+    --http \
+    --http.addr localhost \
     --http.port 8545 \
-    --http.api 'admin,debug,web3,eth,txpool,personal,clique,miner,net' \
-    --verbosity 5 --rpc.gascap 50000000  --rpc.txfeecap 0 \
-    --miner.gaslimit  10 --miner.gasprice 1 --gpo.blocks 1 \
-    --gpo.percentile 1 --gpo.maxprice 10 --gpo.ignoreprice 2 \
+    --http.api 'admin,debug,web3,eth,txpool,personal,miner,net' \
+    --verbosity 5 \
+    --rpc.gascap 50000000 \
+    --rpc.txfeecap 0 \
+    --miner.gaslimit 10 \
+    --miner.gasprice 1 \
+    --gpo.blocks 1 \
+    --gpo.percentile 1 \
+    --gpo.maxprice 10 \
+    --gpo.ignoreprice 2 \
     --dev.gaslimit 50000000
 ```
 
 If we wanted to use erigon for testing, we could do something like this as well.
 
 ```bash
-$ erigon --chain dev --dev.period 5 --http --http.addr localhost \
+$ erigon \
+    --chain dev \
+    --dev.period 5 \
+    --http \
+    --http.addr localhost \
     --http.port 8545 \
-    --http.api 'admin,debug,web3,eth,txpool,personal,clique,miner,net' \
-    --verbosity 5 --rpc.gascap 50000000 \
-    --miner.gaslimit  10 --gpo.blocks 1 \
-    --gpo.percentile 1 --mine
+    --http.api 'admin,debug,web3,eth,txpool,clique,net' \
+    --verbosity 5 \
+    --rpc.gascap 50000000 \
+    --miner.gaslimit 10 \
+    --gpo.blocks 1 \
+    --gpo.percentile 1 \
+    --mine
 ```
 
 Once your Eth client is running and the RPC is functional, you'll need to transfer some amount of ether to a known account that ca be used for testing.
 
 ```
-$ cast send --from "$(cast rpc --rpc-url localhost:8545 eth_coinbase | jq -r '.')" \
-    --rpc-url localhost:8545 --unlocked --value 100ether \
-    0x85dA99c8a7C2C95964c8EfD687E95E632Fc533D6
+$ cast send \
+    --from "$(cast rpc --rpc-url localhost:8545 eth_coinbase | jq -r '.')" \
+    --rpc-url localhost:8545 \
+    --unlocked \
+    --value 100ether \
+    --json \
+    0x85dA99c8a7C2C95964c8EfD687E95E632Fc533D6 | jq
 ```
 
 Then we might want to deploy some test smart contracts. For the purposes of testing we'll our ERC20 contract.
 
 ```bash
-$ cast send --from 0x85dA99c8a7C2C95964c8EfD687E95E632Fc533D6 \
+$ cast send \
+    --from 0x85dA99c8a7C2C95964c8EfD687E95E632Fc533D6 \
     --private-key 0x42b6e34dc21598a807dc19d7784c71b2a7a01f6480dc6f58258f78e539f1a1fa \
-    --rpc-url localhost:8545 --create \
-    "$(cat ./contracts/ERC20.bin)"
+    --rpc-url localhost:8545 \
+    --json \
+    --create \
+    "$(cat ./contracts/tokens/ERC20/ERC20.bin)" | jq
 ```
 
 Once this has been completed this will be the address of the contract: `0x6fda56c57b0acadb96ed5624ac500c0429d59429`.
 
 ```bash
-$  docker run -v $PWD/contracts:/contracts ethereum/solc:stable --storage-layout /contracts/ERC20.sol
+$  docker run -v $PWD/contracts:/contracts ethereum/solc:stable --storage-layout /contracts/tokens/ERC20/ERC20.sol
 ```
 
 ### Links