diff --git a/go.mod b/go.mod
index 7af6dcb..8c3625f 100644
--- a/go.mod
+++ b/go.mod
@@ -14,6 +14,7 @@ require (
 	github.com/sirupsen/logrus v1.9.3
 	github.com/spf13/cobra v1.8.0
 	github.com/wealdtech/go-eth2-wallet-encryptor-keystorev4 v1.1.3
+	golang.org/x/mod v0.21.0
 	gopkg.in/yaml.v2 v2.4.0
 )
 
@@ -131,7 +132,6 @@ require (
 	go.uber.org/zap v1.27.0 // indirect
 	golang.org/x/crypto v0.26.0 // indirect
 	golang.org/x/exp v0.0.0-20240808152545-0cdaa3abc0fa // indirect
-	golang.org/x/mod v0.20.0 // indirect
 	golang.org/x/net v0.28.0 // indirect
 	golang.org/x/oauth2 v0.21.0 // indirect
 	golang.org/x/sync v0.8.0 // indirect
diff --git a/go.sum b/go.sum
index 5f1ed80..7c04079 100644
--- a/go.sum
+++ b/go.sum
@@ -433,8 +433,8 @@ golang.org/x/exp v0.0.0-20240808152545-0cdaa3abc0fa h1:ELnwvuAXPNtPk1TJRuGkI9fDT
 golang.org/x/exp v0.0.0-20240808152545-0cdaa3abc0fa/go.mod h1:akd2r19cwCdwSwWeIdzYQGa/EZZyqcOdwWiwj5L5eKQ=
 golang.org/x/mod v0.2.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/mod v0.3.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
-golang.org/x/mod v0.20.0 h1:utOm6MM3R3dnawAiJgn0y+xvuYRsm1RKM/4giyfDgV0=
-golang.org/x/mod v0.20.0/go.mod h1:hTbmBsO62+eylJbnUtE2MGJUyE7QWk4xUqPFrRgJ+7c=
+golang.org/x/mod v0.21.0 h1:vvrHzRwRfVKSiLrG+d4FMl/Qi4ukBCE6kZlTUkDYRT0=
+golang.org/x/mod v0.21.0/go.mod h1:6SkKJ3Xj0I0BrPOZoBy3bdMptDDU9oJrpohJ3eWZ1fY=
 golang.org/x/net v0.0.0-20180906233101-161cd47e91fd/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
diff --git a/main.go b/main.go
index 9eaa7f4..58d0608 100644
--- a/main.go
+++ b/main.go
@@ -24,6 +24,7 @@ import (
 
 	"github.com/flashbots/mev-boost-relay/beaconclient"
 	mevRCommon "github.com/flashbots/mev-boost-relay/common"
+	"golang.org/x/mod/semver"
 
 	"github.com/ethereum/go-ethereum/core/types"
 	ecrypto "github.com/ethereum/go-ethereum/crypto"
@@ -58,6 +59,7 @@ var validateFlag bool
 var genesisDelayFlag uint64
 var watchPayloadsFlag bool
 var latestForkFlag bool
+var useRethForValidation bool
 
 var rootCmd = &cobra.Command{
 	Use:   "playground",
@@ -164,6 +166,7 @@ func main() {
 	rootCmd.Flags().Uint64Var(&genesisDelayFlag, "genesis-delay", 5, "")
 	rootCmd.Flags().BoolVar(&watchPayloadsFlag, "watch-payloads", false, "")
 	rootCmd.Flags().BoolVar(&latestForkFlag, "electra", false, "")
+	rootCmd.Flags().BoolVar(&useRethForValidation, "use-reth-for-validation", false, "enable flashbots_validateBuilderSubmissionV* on reth and use them for validation")
 
 	downloadArtifactsCmd.Flags().BoolVar(&validateFlag, "validate", false, "")
 	validateCmd.Flags().Uint64Var(&numBlocksValidate, "num-blocks", 5, "")
@@ -361,12 +364,32 @@ func setupServices(svcManager *serviceManager, out *output) error {
 		fmt.Printf("(%d) %s (%s)\n", indx, acc, ecrypto.PubkeyToAddress(priv.PublicKey).Hex())
 	}
 	fmt.Println("")
-
 	if err := os.WriteFile(defaultRethDiscoveryPrivKeyLoc, []byte(defaultRethDiscoveryPrivKey), 0644); err != nil {
 		return err
 	}
 
+	rethVersion := func() string {
+		cmd := exec.Command(rethBin, "--version")
+		out, err := cmd.Output()
+		if err != nil {
+			return "unknown"
+		}
+		// find the line of the form:
+		// reth Version: x.y.z
+		for _, line := range strings.Split(string(out), "\n") {
+			if strings.HasPrefix(line, "reth Version: ") {
+				v := strings.TrimSpace(strings.TrimPrefix(line, "reth Version: "))
+				if !strings.HasPrefix(v, "v") {
+					v = "v" + v
+				}
+				return semver.Canonical(v)
+			}
+		}
+		return "unknown"
+	}()
+
 	// start the reth el client
+	fmt.Println("Starting reth version " + rethVersion)
 	svcManager.
 		NewService("reth").
 		WithArgs(
@@ -387,6 +410,16 @@ func setupServices(svcManager *serviceManager, out *output) error {
 			"--authrpc.port", "8551",
 			"--authrpc.jwtsecret", "{{.Dir}}/jwtsecret",
 		).
+		If(useRethForValidation, func(s *service) *service {
+			return s.WithArgs("--http.api", "eth,web3,net,rpc,flashbots")
+		}).
+		If(
+			semver.Compare(rethVersion, "v1.1.0") >= 0,
+			func(s *service) *service {
+				// For versions >= v1.1.0, we need to run with --engine.legacy, at least for now
+				return s.WithArgs("--engine.legacy")
+			},
+		).
 		WithPort("rpc", 30303).
 		WithPort("http", 8545).
 		WithPort("authrpc", 8551).
@@ -444,6 +477,7 @@ func setupServices(svcManager *serviceManager, out *output) error {
 		if cfg.LogOutput, err = out.LogOutput("mev-boost-relay"); err != nil {
 			return err
 		}
+		cfg.UseRethForValidation = useRethForValidation
 		relay, err := mevboostrelay.New(cfg)
 		if err != nil {
 			return fmt.Errorf("failed to create relay: %w", err)
@@ -731,6 +765,13 @@ func (s *service) WithArgs(args ...string) *service {
 	return s
 }
 
+func (s *service) If(cond bool, fn func(*service) *service) *service {
+	if cond {
+		return fn(s)
+	}
+	return s
+}
+
 func (s *service) Run() {
 	s.srvMng.Run(s)
 }
diff --git a/mev-boost-relay/mev-boost-relay.go b/mev-boost-relay/mev-boost-relay.go
index 2e64dde..0975800 100644
--- a/mev-boost-relay/mev-boost-relay.go
+++ b/mev-boost-relay/mev-boost-relay.go
@@ -33,15 +33,18 @@ type Config struct {
 	ApiSecretKey     string
 	BeaconClientAddr string
 	LogOutput        io.Writer
+
+	UseRethForValidation bool
 }
 
 func DefaultConfig() *Config {
 	return &Config{
-		ApiListenAddr:    "127.0.0.1",
-		ApiListenPort:    5555,
-		ApiSecretKey:     defaultSecretKey,
-		BeaconClientAddr: "http://localhost:3500",
-		LogOutput:        os.Stdout,
+		ApiListenAddr:        "127.0.0.1",
+		ApiListenPort:        5555,
+		ApiSecretKey:         defaultSecretKey,
+		BeaconClientAddr:     "http://localhost:3500",
+		LogOutput:            os.Stdout,
+		UseRethForValidation: false,
 	}
 }
 
@@ -119,13 +122,20 @@ func New(config *Config) (*MevBoostRelay, error) {
 
 	housekeeperSrv := housekeeper.NewHousekeeper(housekeeperOpts)
 
-	// start a mock block validation service that always
-	// returns the blocks as valids.
-	apiBlockSimURL, err := startMockBlockValidationServiceServer()
-	if err != nil {
-		return nil, fmt.Errorf("failed to start mock block validation service: %w", err)
+	var blockSimURL string
+	if config.UseRethForValidation {
+		log.Info("Using reth for block validation")
+		blockSimURL = "http://localhost:8545"
+	} else {
+		// start a mock block validation service that always
+		// returns the blocks as valids.
+		apiBlockSimURL, err := startMockBlockValidationServiceServer()
+		if err != nil {
+			return nil, fmt.Errorf("failed to start mock block validation service: %w", err)
+		}
+		log.Info("Started mock block validation service, addr: ", apiBlockSimURL)
+		blockSimURL = apiBlockSimURL
 	}
-	log.Info("Started mock block validation service, addr: ", apiBlockSimURL)
 
 	// decode the secret key
 	envSkBytes, err := hex.DecodeString(strings.TrimPrefix(config.ApiSecretKey, "0x"))
@@ -146,7 +156,7 @@ func New(config *Config) (*MevBoostRelay, error) {
 		DB:              pqDB,
 		SecretKey:       secretKey,
 		EthNetDetails:   *ethNetworkDetails,
-		BlockSimURL:     apiBlockSimURL,
+		BlockSimURL:     blockSimURL,
 		ProposerAPI:     true,
 		BlockBuilderAPI: true,
 		DataAPI:         true,