diff --git a/conn.go b/conn.go
index 22afb78..be4b811 100644
--- a/conn.go
+++ b/conn.go
@@ -4,7 +4,9 @@ import (
 	"encoding/binary"
 	"io"
 	"net"
+	"reflect"
 	"sync"
+	"sync/atomic"
 	"time"
 )
 
@@ -14,23 +16,30 @@ var DefaultFirstFragmentLen = 4
 // Conn remote: real server; local: relay
 type Conn struct {
 	relay relay
+	isold uintptr
 	init  *sync.Once
 	conn  *net.TCPConn
-	isold bool
 }
 
 // NewConn wraps *net.TCPConn (net.Conn must be *net.TCPConn)
 func NewConn(conn net.Conn) *Conn {
-	return &Conn{
+	c := &Conn{
 		relay: newrelay(),
 		init:  &sync.Once{},
 		conn:  conn.(*net.TCPConn),
 	}
+	switch o := conn.(type) {
+	case *net.TCPConn:
+		c.conn = o
+	default:
+		panic("unsupported conn type: " + reflect.TypeOf(conn).String())
+	}
+	return c
 }
 
 // Write is send
 func (conn *Conn) Write(b []byte) (int, error) {
-	if conn.isold || DefaultFirstFragmentLen == 0 {
+	if atomic.LoadUintptr(&conn.isold) != 0 || DefaultFirstFragmentLen == 0 {
 		return conn.conn.Write(b)
 	}
 	go conn.init.Do(func() {
@@ -44,10 +53,12 @@ func (conn *Conn) Write(b []byte) (int, error) {
 
 // ReadFrom when client want to send to server, detect and split.
 func (conn *Conn) ReadFrom(r io.Reader) (n int64, err error) {
-	if conn.isold || DefaultFirstFragmentLen == 0 {
+	if atomic.LoadUintptr(&conn.isold) != 0 || DefaultFirstFragmentLen == 0 {
 		return conn.conn.ReadFrom(r)
 	}
 
+	defer atomic.StoreUintptr(&conn.isold, 1)
+
 	// ContentType [0:1]
 	// Version [1:3]
 	// Length [3:5]
@@ -61,10 +72,6 @@ func (conn *Conn) ReadFrom(r io.Reader) (n int64, err error) {
 	var b []byte
 	bd := newbuilder()
 
-	defer func() {
-		conn.isold = true
-	}()
-
 	// ContentType [0:1] Version [1:2] 0x03
 	_, err = io.ReadFull(r, header[:2])
 	if err != nil {
diff --git a/dns/dns.go b/dns/dns.go
index 2289904..dcc5f5c 100644
--- a/dns/dns.go
+++ b/dns/dns.go
@@ -89,6 +89,14 @@ type List struct {
 	b       map[string][]string
 }
 
+// NewEmptyList ...
+func NewEmptyList() *List {
+	return &List{
+		m: make(map[string][]*dnsstat, 64),
+		b: make(map[string][]string, 64),
+	}
+}
+
 // Config is the user config
 type Config struct {
 	Servers   map[string][]string `yaml:"Servers"`   // Servers map[dot.com]ip:ports
diff --git a/go.mod b/go.mod
index b482806..02bfbe7 100644
--- a/go.mod
+++ b/go.mod
@@ -4,11 +4,23 @@ go 1.22
 
 require (
 	github.com/FloatTech/ttl v0.0.0-20250224045156-012b1463287d
+	github.com/fumiama/go-base16384 v1.7.1
+	github.com/quic-go/quic-go v0.49.1-0.20250213113345-5af39164b9fe
 	github.com/sirupsen/logrus v1.9.3
-	golang.org/x/net v0.24.0
+	golang.org/x/net v0.28.0
 )
 
 require (
-	golang.org/x/sys v0.19.0 // indirect
-	golang.org/x/text v0.14.0 // indirect
+	github.com/go-task/slim-sprig v0.0.0-20230315185526-52ccab3ef572 // indirect
+	github.com/google/pprof v0.0.0-20210407192527-94a9f03dee38 // indirect
+	github.com/onsi/ginkgo/v2 v2.9.5 // indirect
+	github.com/quic-go/qpack v0.5.1 // indirect
+	go.uber.org/mock v0.5.0 // indirect
+	golang.org/x/crypto v0.26.0 // indirect
+	golang.org/x/exp v0.0.0-20240506185415-9bf2ced13842 // indirect
+	golang.org/x/mod v0.18.0 // indirect
+	golang.org/x/sync v0.8.0 // indirect
+	golang.org/x/sys v0.23.0 // indirect
+	golang.org/x/text v0.17.0 // indirect
+	golang.org/x/tools v0.22.0 // indirect
 )
diff --git a/go.sum b/go.sum
index 6d0797c..3318cb0 100644
--- a/go.sum
+++ b/go.sum
@@ -1,22 +1,69 @@
 github.com/FloatTech/ttl v0.0.0-20250224045156-012b1463287d h1:mUQ/c3wXKsUGa4Sg9DBy01APXKB68PmobhxOyaJI7lY=
 github.com/FloatTech/ttl v0.0.0-20250224045156-012b1463287d/go.mod h1:fHZFWGquNXuHttu9dUYoKuNbm3dzLETnIOnm1muSfDs=
+github.com/chzyer/logex v1.1.10/go.mod h1:+Ywpsq7O8HXn0nuIou7OrIPyXbp3wmkHB+jjWRnGsAI=
+github.com/chzyer/readline v0.0.0-20180603132655-2972be24d48e/go.mod h1:nSuG5e5PlCu98SY8svDHJxuZscDgtXS6KTTbou5AhLI=
+github.com/chzyer/test v0.0.0-20180213035817-a1ea475d72b1/go.mod h1:Q3SI9o4m/ZMnBNeIyt5eFwwo7qiLfzFZmjNmxjkiQlU=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/fumiama/go-base16384 v1.7.1 h1:1P1x6FWRvd7PtbH4idDAGWAjKKcVxggxlROYKRXbw58=
+github.com/fumiama/go-base16384 v1.7.1/go.mod h1:OEn+947GV5gsbTAnyuUW/SrfxJYUdYupSIQXOuGOcXM=
+github.com/go-logr/logr v1.2.4 h1:g01GSCwiDw2xSZfjJ2/T9M+S6pFdcNtFYsp+Y43HYDQ=
+github.com/go-logr/logr v1.2.4/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
+github.com/go-task/slim-sprig v0.0.0-20230315185526-52ccab3ef572 h1:tfuBGBXKqDEevZMzYi5KSi8KkcZtzBcTgAUUtapy0OI=
+github.com/go-task/slim-sprig v0.0.0-20230315185526-52ccab3ef572/go.mod h1:9Pwr4B2jHnOSGXyyzV8ROjYa2ojvAY6HCGYYfMoC3Ls=
+github.com/golang/protobuf v1.5.3 h1:KhyjKVUg7Usr/dYsdSqoFveMYd5ko72D+zANwlG1mmg=
+github.com/golang/protobuf v1.5.3/go.mod h1:XVQd3VNwM+JqD3oG2Ue2ip4fOMUkwXdXDdiuN0vRsmY=
+github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
+github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
+github.com/google/pprof v0.0.0-20210407192527-94a9f03dee38 h1:yAJXTCF9TqKcTiHJAE8dj7HMvPfh66eeA2JYW7eFpSE=
+github.com/google/pprof v0.0.0-20210407192527-94a9f03dee38/go.mod h1:kpwsk12EmLew5upagYY7GY0pfYCcupk39gWOCRROcvE=
+github.com/ianlancetaylor/demangle v0.0.0-20200824232613-28f6c0f3b639/go.mod h1:aSSvb/t6k1mPoxDqO4vJh6VOCGPwU4O0C2/Eqndh1Sc=
+github.com/onsi/ginkgo/v2 v2.9.5 h1:+6Hr4uxzP4XIUyAkg61dWBw8lb/gc4/X5luuxN/EC+Q=
+github.com/onsi/ginkgo/v2 v2.9.5/go.mod h1:tvAoo1QUJwNEU2ITftXTpR7R1RbCzoZUOs3RonqW57k=
+github.com/onsi/gomega v1.27.6 h1:ENqfyGeS5AX/rlXDd/ETokDz93u0YufY1Pgxuy/PvWE=
+github.com/onsi/gomega v1.27.6/go.mod h1:PIQNjfQwkP3aQAH7lf7j87O/5FiNr+ZR8+ipb+qQlhg=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/quic-go/qpack v0.5.1 h1:giqksBPnT/HDtZ6VhtFKgoLOWmlyo9Ei6u9PqzIMbhI=
+github.com/quic-go/qpack v0.5.1/go.mod h1:+PC4XFrEskIVkcLzpEkbLqq1uCoxPhQuvK5rH1ZgaEg=
+github.com/quic-go/quic-go v0.49.1-0.20250213113345-5af39164b9fe h1:gaj0z36YmZoU5opm6XIK20Vn18jDB6AxbjUXCd732k0=
+github.com/quic-go/quic-go v0.49.1-0.20250213113345-5af39164b9fe/go.mod h1:s2wDnmCdooUQBmQfpUSTCYBl1/D4FcqbULMMkASvR6s=
 github.com/sirupsen/logrus v1.9.3 h1:dueUQJ1C2q9oE3F7wvmSGAaVtTmUizReu6fjN8uqzbQ=
 github.com/sirupsen/logrus v1.9.3/go.mod h1:naHLuLoDiP4jHNo9R0sCBMtWGeIprob74mVsIT4qYEQ=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
-github.com/stretchr/testify v1.8.0 h1:pSgiaMZlXftHpm5L7V1+rVB+AZJydKsMxsQBIJw4PKk=
-golang.org/x/net v0.24.0 h1:1PcaxkF854Fu3+lvBIx5SYn9wRlBzzcnHZSiaFFAb0w=
-golang.org/x/net v0.24.0/go.mod h1:2Q7sJY5mzlzWjKtYUEXSlBWCdyaioyXzRB2RtU8KVE8=
+github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
+github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+go.uber.org/mock v0.5.0 h1:KAMbZvZPyBPWgD14IrIQ38QCyjwpvVVV6K/bHl1IwQU=
+go.uber.org/mock v0.5.0/go.mod h1:ge71pBPLYDk7QIi1LupWxdAykm7KIEFchiOqd6z7qMM=
+golang.org/x/crypto v0.26.0 h1:RrRspgV4mU+YwB4FYnuBoKsUapNIL5cohGAmSH3azsw=
+golang.org/x/crypto v0.26.0/go.mod h1:GY7jblb9wI+FOo5y8/S2oY4zWP07AkOJ4+jxCqdqn54=
+golang.org/x/exp v0.0.0-20240506185415-9bf2ced13842 h1:vr/HnozRka3pE4EsMEg1lgkXJkTFJCVUX+S/ZT6wYzM=
+golang.org/x/exp v0.0.0-20240506185415-9bf2ced13842/go.mod h1:XtvwrStGgqGPLc4cjQfWqZHG1YFdYs6swckp8vpsjnc=
+golang.org/x/mod v0.18.0 h1:5+9lSbEzPSdWkH32vYPBwEpX8KwDbM52Ud9xBUvNlb0=
+golang.org/x/mod v0.18.0/go.mod h1:hTbmBsO62+eylJbnUtE2MGJUyE7QWk4xUqPFrRgJ+7c=
+golang.org/x/net v0.28.0 h1:a9JDOJc5GMUJ0+UDqmLT86WiEy7iWyIhz8gz8E4e5hE=
+golang.org/x/net v0.28.0/go.mod h1:yqtgsTWOOnlGLG9GFRrK3++bGOUEkNBoHZc8MEDWPNg=
+golang.org/x/sync v0.8.0 h1:3NFvSEYkUoMifnESzZl15y791HH1qU2xm6eCJU5ZPXQ=
+golang.org/x/sync v0.8.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
+golang.org/x/sys v0.0.0-20191204072324-ce4227a45e2e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.19.0 h1:q5f1RH2jigJ1MoAWp2KTp3gm5zAGFUTarQZ5U386+4o=
-golang.org/x/sys v0.19.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
-golang.org/x/text v0.14.0 h1:ScX5w1eTa3QqT8oi6+ziP7dTV1S2+ALU0bI+0zXKWiQ=
-golang.org/x/text v0.14.0/go.mod h1:18ZOQIKpY8NJVqYksKHtTdi31H5itFRjB5/qKTNYzSU=
+golang.org/x/sys v0.23.0 h1:YfKFowiIMvtgl1UERQoTPPToxltDeZfbj4H7dVUCwmM=
+golang.org/x/sys v0.23.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
+golang.org/x/text v0.17.0 h1:XtiM5bkSOt+ewxlOE/aE/AKEHibwj/6gvWMl9Rsh0Qc=
+golang.org/x/text v0.17.0/go.mod h1:BuEKDfySbSR4drPmRPG/7iBdf8hvFMuRexcpahXilzY=
+golang.org/x/time v0.5.0 h1:o7cqy6amK/52YcAKIPlM3a+Fpj35zvRj2TP+e1xFSfk=
+golang.org/x/time v0.5.0/go.mod h1:3BpzKBy/shNhVucY/MWOyx10tF3SFh9QdLuxbVysPQM=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+golang.org/x/tools v0.22.0 h1:gqSGLZqv+AI9lIQzniJ0nZDRG5GBPsSi+DRNHWNz6yA=
+golang.org/x/tools v0.22.0/go.mod h1:aCwcsjqvq7Yqt6TNyX7QMU2enbQ/Gt0bo6krSeEri+c=
+google.golang.org/protobuf v1.33.0 h1:uNO2rsAINq/JlFpSdYEKIZ0uKD/R9cpdv0T+yoGwGmI=
+google.golang.org/protobuf v1.33.0/go.mod h1:c6P6GXX6sHbq/GpV6MGZEdwhWPcYBgnhAHhKbcUYpos=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/http2/http2.go b/http2/http.go
similarity index 100%
rename from http2/http2.go
rename to http2/http.go
diff --git a/http2/http2_test.go b/http2/http_test.go
similarity index 100%
rename from http2/http2_test.go
rename to http2/http_test.go
diff --git a/http3/http.go b/http3/http.go
new file mode 100644
index 0000000..014d652
--- /dev/null
+++ b/http3/http.go
@@ -0,0 +1,117 @@
+// Package http3 is the same as the standard http lib with HTTP3 client support
+package http3
+
+import (
+	"bytes"
+	"context"
+	"crypto/rand"
+	"crypto/tls"
+	"errors"
+	"io"
+	mrand "math/rand"
+	"net"
+	"net/http"
+	"net/netip"
+	"net/url"
+	"time"
+
+	base14 "github.com/fumiama/go-base16384"
+	"github.com/fumiama/terasu/dns"
+	"github.com/quic-go/quic-go"
+	"github.com/quic-go/quic-go/http3"
+)
+
+// ErrEmptyHostAddress is returned when DNS lookup for a host returns no addresses
+var ErrEmptyHostAddress = errors.New("empty host addr")
+
+// defaultDialer is the default dialer used for establishing TCP connections
+var defaultDialer = net.Dialer{
+	Timeout: 10 * time.Second,
+}
+
+// SetDefaultClientTimeout sets the default timeout for all HTTP2 client connections
+func SetDefaultClientTimeout(t time.Duration) {
+	defaultDialer.Timeout = t
+}
+
+// DefaultClient is the default HTTP2 client that supports HTTP/2 and DNS resolution
+var DefaultClient = http.Client{
+	Transport: &http3.Transport{
+		Dial: func(ctx context.Context, addr string, tlsCfg *tls.Config, cfg *quic.Config) (quic.EarlyConnection, error) {
+			host, port, err := net.SplitHostPort(addr)
+			if err != nil {
+				return nil, err
+			}
+			addrs, err := dns.LookupHost(ctx, host)
+			if err != nil {
+				return nil, err
+			}
+			if len(addrs) == 0 {
+				return nil, ErrEmptyHostAddress
+			}
+			var conn net.Conn
+			var qConn quic.EarlyConnection
+			for _, a := range addrs {
+				if defaultDialer.Timeout != 0 {
+					var cancel context.CancelFunc
+					ctx, cancel = context.WithTimeout(context.Background(), defaultDialer.Timeout)
+					defer cancel()
+				} else if !defaultDialer.Deadline.IsZero() {
+					var cancel context.CancelFunc
+					ctx, cancel = context.WithDeadline(context.Background(), defaultDialer.Deadline)
+					defer cancel()
+				}
+				conn, err = net.ListenUDP("udp", nil)
+				if err != nil {
+					continue
+				}
+				ucon := conn.(*net.UDPConn)
+				raddr := net.UDPAddrFromAddrPort(
+					netip.MustParseAddrPort(net.JoinHostPort(a, port)),
+				)
+				n := (mrand.Intn(128) + 128) / 7 * 14
+				w := bytes.NewBuffer(make([]byte, 0, base14.EncodeLen(n)))
+				e := base14.NewEncoder(w)
+				_, _ = io.CopyN(e, rand.Reader, int64(n))
+				_ = e.Close()
+				_, _ = ucon.WriteToUDP(w.Bytes(), raddr)
+				// re-init ctx due to deadline settings in tcp dial
+				if defaultDialer.Timeout != 0 {
+					var cancel context.CancelFunc
+					ctx, cancel = context.WithTimeout(context.Background(), defaultDialer.Timeout)
+					defer cancel()
+				} else if !defaultDialer.Deadline.IsZero() {
+					var cancel context.CancelFunc
+					ctx, cancel = context.WithDeadline(context.Background(), defaultDialer.Deadline)
+					defer cancel()
+				}
+				qConn, err = quic.DialEarly(ctx, ucon, raddr, tlsCfg, cfg)
+				if err == nil {
+					break
+				}
+				panic(err)
+			}
+			return qConn, err
+		},
+	},
+}
+
+// Get sends an HTTP GET request to the specified URL using the default HTTP2 client
+func Get(url string) (resp *http.Response, err error) {
+	return DefaultClient.Get(url)
+}
+
+// Head sends an HTTP HEAD request to the specified URL using the default HTTP2 client
+func Head(url string) (resp *http.Response, err error) {
+	return DefaultClient.Head(url)
+}
+
+// Post sends an HTTP POST request to the specified URL with the given content type and body using the default HTTP2 client
+func Post(url string, contentType string, body io.Reader) (resp *http.Response, err error) {
+	return DefaultClient.Post(url, contentType, body)
+}
+
+// PostForm sends an HTTP POST request with form data to the specified URL using the default HTTP2 client
+func PostForm(url string, data url.Values) (resp *http.Response, err error) {
+	return DefaultClient.PostForm(url, data)
+}
diff --git a/http3/http_test.go b/http3/http_test.go
new file mode 100644
index 0000000..d228b59
--- /dev/null
+++ b/http3/http_test.go
@@ -0,0 +1,37 @@
+package http3
+
+import (
+	"io"
+	"testing"
+
+	"github.com/fumiama/terasu/dns"
+)
+
+func TestClientGet(t *testing.T) {
+	dns.IPv4Servers = *dns.NewEmptyList()
+	dns.IPv6Servers = *dns.NewEmptyList()
+	dns.IPv4Servers.Add(&dns.Config{
+		Fallbacks: map[string][]string{
+			"huggingface.co": {"52.222.136.117"},
+		},
+	})
+	resp, err := Get("https://huggingface.co/")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	t.Log("[T] response code", resp.StatusCode)
+	for k, vs := range resp.Header {
+		for _, v := range vs {
+			t.Log("[T] response header", k+":", v)
+		}
+	}
+	data, err := io.ReadAll(resp.Body)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(data) == 0 {
+		t.Fail()
+	}
+	t.Log(string(data))
+}