diff --git a/examples/.gitignore b/examples/.gitignore
new file mode 100644
index 0000000..8b3231d
--- /dev/null
+++ b/examples/.gitignore
@@ -0,0 +1,5 @@
+*.pb.go
+*.pd
+
+/gateway/gateway
+/helloworld/server/server
diff --git a/examples/gateway/main.go b/examples/gateway/main.go
new file mode 100644
index 0000000..73b3355
--- /dev/null
+++ b/examples/gateway/main.go
@@ -0,0 +1,137 @@
+package main
+
+import (
+	"encoding/json"
+	"flag"
+	"log"
+	"net/http"
+	"os"
+
+	"github.com/vizee/gapi/engine"
+	"github.com/vizee/gapi/handlers/httpview"
+	"github.com/vizee/gapi/handlers/jsonapi"
+	"github.com/vizee/gapi/metadata"
+	"github.com/vizee/gapi/proto/descriptor"
+	"google.golang.org/grpc/status"
+	"google.golang.org/protobuf/proto"
+	"google.golang.org/protobuf/types/descriptorpb"
+)
+
+func writeJsonResponse(w http.ResponseWriter, o any) {
+	w.Header().Set("Content-Type", "application/json")
+	data, _ := json.Marshal(o)
+	_, _ = w.Write(data)
+}
+
+func newEngine() *engine.Engine {
+	builder := engine.NewBuilder()
+
+	builder.RegisterHandler("httpview", &httpview.Handler{
+		PassPath:      true,
+		PassQuery:     true,
+		PassParams:    true,
+		CopyHeaders:   true,
+		FilterHeaders: []string{"Content-Type", "User-Agent"},
+		MaxBodySize:   1 * 1024 * 1024,
+	})
+	builder.RegisterHandler("jsonapi", &jsonapi.Handler{})
+
+	builder.RegisterMiddleware("sign", func(ctx *engine.Context) error {
+		sign := ctx.Request().URL.Query().Get("sign")
+		if sign == "good" {
+			return ctx.Next()
+		} else {
+			http.Error(ctx.Response(), http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
+			return nil
+		}
+	})
+
+	builder.RegisterMiddleware("auth", func(ctx *engine.Context) error {
+		uid := ctx.Request().URL.Query().Get("uid")
+		if uid != "" {
+			ctx.Set("uid", uid)
+			return ctx.Next()
+		} else {
+			http.Error(ctx.Response(), http.StatusText(http.StatusUnauthorized), http.StatusUnauthorized)
+			return nil
+		}
+	})
+
+	builder.Use(func(ctx *engine.Context) error {
+		log.Printf("<> %s %s", ctx.Request().Method, ctx.Request().URL.String())
+		return ctx.Next()
+	})
+	builder.Use(func(ctx *engine.Context) error {
+		err := ctx.Next()
+		if err != nil {
+			if s, ok := status.FromError(err); ok {
+				if s.Code() >= 1000 {
+					writeJsonResponse(ctx.Response(), map[string]any{
+						"code":    s.Code(),
+						"message": s.Message(),
+					})
+					return nil
+				}
+			}
+			log.Printf("ERROR %s %v", ctx.Request().RequestURI, err)
+			http.Error(ctx.Response(), http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
+		}
+		return nil
+	})
+
+	builder.NotFound(func(ctx *engine.Context) error {
+		http.NotFound(ctx.Response(), ctx.Request())
+		return nil
+	})
+
+	return builder.Build()
+}
+
+func loadRoutes(fname string) ([]metadata.Route, error) {
+	data, err := os.ReadFile(fname)
+	if err != nil {
+		return nil, err
+	}
+
+	var fds descriptorpb.FileDescriptorSet
+	err = proto.Unmarshal(data, &fds)
+	if err != nil {
+		return nil, err
+	}
+	p := descriptor.NewParser()
+	for _, fd := range fds.File {
+		err := p.AddFile(fd)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return metadata.ResolveRoutes(&metadata.MessageCache{}, p.Services(), false)
+}
+
+func main() {
+	var (
+		pdFile     string
+		listenAddr string
+	)
+	flag.StringVar(&pdFile, "pd", "file.pd", "pd file")
+	flag.StringVar(&listenAddr, "l", ":8080", "listen address")
+	flag.Parse()
+
+	engine := newEngine()
+	routes, err := loadRoutes(pdFile)
+	if err != nil {
+		log.Fatalf("loadRoutes: %v", err)
+	}
+	err = engine.RebuildRouter(routes, false)
+	if err != nil {
+		log.Fatalf("RebuildRouter: %v", err)
+	}
+
+	log.Printf("listening: %s", listenAddr)
+
+	err = http.ListenAndServe(listenAddr, engine)
+	if err != nil {
+		log.Fatalf("srv.ListenAndServe: %v", err)
+	}
+}
diff --git a/examples/helloworld/proto/Makefile b/examples/helloworld/proto/Makefile
new file mode 100644
index 0000000..86c628c
--- /dev/null
+++ b/examples/helloworld/proto/Makefile
@@ -0,0 +1,6 @@
+GAPI_PROTO ?= .
+
+proto:
+	@protoc -I . -I $(GAPI_PROTO) --descriptor_set_out=helloworld.pd \
+		--go_out=. --go_opt=paths=source_relative \
+		--go-grpc_out=. --go-grpc_opt=paths=source_relative helloworld.proto
diff --git a/examples/helloworld/proto/helloworld.proto b/examples/helloworld/proto/helloworld.proto
new file mode 100644
index 0000000..0a350aa
--- /dev/null
+++ b/examples/helloworld/proto/helloworld.proto
@@ -0,0 +1,31 @@
+syntax = "proto3";
+
+package gapi.examples.helloworld.proto;
+
+option go_package = "github.com/vizee/gapi/examples/helloworld/proto";
+
+import "gapi/annotation.proto";
+
+service Greeter {
+    option (gapi.server) = "localhost:50051";
+    option (gapi.default_handler) = "jsonapi";
+    option (gapi.default_timeout) = 5000;
+    option (gapi.path_prefix) = "/greeter";
+    option (gapi.use) = "sign";
+
+    rpc SayHello (HelloRequest) returns (HelloReply) {
+        option (gapi.http) = {
+            post: "/sayHello"
+            use: "auth"
+        };
+    }
+}
+
+message HelloRequest {
+    string name = 1;
+    string userId = 2 [(gapi.alias) = "uid", (gapi.bind) = FROM_CONTEXT];
+}
+
+message HelloReply {
+    string message = 1;
+}
diff --git a/examples/helloworld/server/main.go b/examples/helloworld/server/main.go
new file mode 100644
index 0000000..3c401db
--- /dev/null
+++ b/examples/helloworld/server/main.go
@@ -0,0 +1,46 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"net"
+
+	"github.com/vizee/gapi/examples/helloworld/proto"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/status"
+)
+
+type Greeter struct {
+	proto.UnimplementedGreeterServer
+}
+
+func (*Greeter) SayHello(ctx context.Context, req *proto.HelloRequest) (*proto.HelloReply, error) {
+	log.Printf("SayHello: %s", req)
+
+	if len(req.Name) < 3 {
+		return nil, status.Errorf(1000, "name too short")
+	}
+
+	return &proto.HelloReply{
+		Message: fmt.Sprintf("Hello %s(%s)", req.Name, req.UserId),
+	}, nil
+}
+
+func main() {
+	const listenAddr = ":50051"
+
+	srv := grpc.NewServer()
+	proto.RegisterGreeterServer(srv, &Greeter{})
+	ln, err := net.Listen("tcp", listenAddr)
+	if err != nil {
+		log.Fatalf("listen: %v", err)
+	}
+
+	log.Printf("listening: %s", listenAddr)
+
+	err = srv.Serve(ln)
+	if err != nil {
+		log.Fatalf("serve: %v", err)
+	}
+}