diff --git a/_examples/queues/README.md b/_examples/queues/README.md
new file mode 100644
index 0000000..cfb6ef9
--- /dev/null
+++ b/_examples/queues/README.md
@@ -0,0 +1,38 @@
+# queues
+
+An example of using Cloudflare Workers that interact with [Cloudflare Queues](https://developers.cloudflare.com/queues/).
+
+## Running
+
+### Requirements
+
+This project requires these tools to be installed globally.
+
+* wrangler
+* tinygo
+
+### Supported commands
+
+```
+make dev     # run dev server
+make build   # build Go Wasm binary
+make deploy # deploy worker
+```
+
+### Interacting with the local queue
+
+1. Start the dev server.
+```sh
+make dev
+```
+
+2. Send a message to the queue.
+```sh
+curl -v -X POST http://localhost:8787/ -d '{"message": "Hello, World!"}' -H "Content-Type: application/json"
+```
+
+3. Observe the response and server logs
+
+4. You can pass `text/plain` content type to write queue message as the string or omit the `Content-Type` header to write queue message as 
+byte array.
+
diff --git a/cloudflare/queues/content_type.go b/cloudflare/queues/content_type.go
index f68102a..b0db97a 100644
--- a/cloudflare/queues/content_type.go
+++ b/cloudflare/queues/content_type.go
@@ -8,13 +8,29 @@ import (
 	"github.com/syumai/workers/internal/jsutil"
 )
 
+// QueueContentType represents the content type of a message produced to a queue.
+// This information mostly affects how the message body is represented in the Cloudflare UI and is NOT
+// propagated to the consumer side.
+//   - https://developers.cloudflare.com/queues/configuration/javascript-apis/#queuescontenttype
 type QueueContentType string
 
 const (
-	QueueContentTypeJSON  QueueContentType = "json"
-	QueueContentTypeText  QueueContentType = "text"
+	// QueueContentTypeJSON is the default content type for the produced queue message.
+	// The message body is NOT being marshaled before sending and is passed to js.ValueOf directly.
+	// Make sure the body is serializable to JSON.
+	//  - https://pkg.go.dev/syscall/js#ValueOf
+	QueueContentTypeJSON QueueContentType = "json"
+
+	// QueueContentTypeV8 is currently treated the same as QueueContentTypeJSON.
+	QueueContentTypeV8 QueueContentType = "v8"
+
+	// QueueContentTypeText is used to send a message as a string.
+	// Supported body types are string, []byte and io.Reader.
+	QueueContentTypeText QueueContentType = "text"
+
+	// QueueContentTypeBytes is used to send a message as a byte array.
+	// Supported body types are string, []byte, and io.Reader.
 	QueueContentTypeBytes QueueContentType = "bytes"
-	QueueContentTypeV8    QueueContentType = "v8"
 )
 
 func (o QueueContentType) mapValue(val any) (js.Value, error) {
@@ -25,6 +41,12 @@ func (o QueueContentType) mapValue(val any) (js.Value, error) {
 			return js.ValueOf(v), nil
 		case []byte:
 			return js.ValueOf(string(v)), nil
+		case io.Reader:
+			b, err := io.ReadAll(v)
+			if err != nil {
+				return js.Undefined(), fmt.Errorf("failed to read bytes from reader: %w", err)
+			}
+			return js.ValueOf(string(b)), nil
 		default:
 			return js.Undefined(), fmt.Errorf("invalid value type for text content type: %T", val)
 		}
diff --git a/cloudflare/queues/content_type_test.go b/cloudflare/queues/content_type_test.go
new file mode 100644
index 0000000..5305c97
--- /dev/null
+++ b/cloudflare/queues/content_type_test.go
@@ -0,0 +1,205 @@
+package queues
+
+import (
+	"bytes"
+	"syscall/js"
+	"testing"
+
+	"github.com/syumai/workers/internal/jsutil"
+)
+
+func TestContentType_mapValue(t *testing.T) {
+	tests := []struct {
+		name        string
+		contentType QueueContentType
+		val         any
+		want        js.Value
+		wantErr     bool
+	}{
+		{
+			name:        "string as text",
+			contentType: QueueContentTypeText,
+			val:         "hello",
+			want:        js.ValueOf("hello"),
+		},
+		{
+			name:        "[]byte as text",
+			contentType: QueueContentTypeText,
+			val:         []byte("hello"),
+			want:        js.ValueOf("hello"),
+		},
+		{
+			name:        "io.Reader as text",
+			contentType: QueueContentTypeText,
+			val:         bytes.NewBufferString("hello"),
+			want:        js.ValueOf("hello"),
+		},
+		{
+			name:        "number as text",
+			contentType: QueueContentTypeText,
+			val:         42,
+			want:        js.Undefined(),
+			wantErr:     true,
+		},
+		{
+			name:        "function as text",
+			contentType: QueueContentTypeText,
+			val:         func() {},
+			want:        js.Undefined(),
+			wantErr:     true,
+		},
+
+		{
+			name:        "string as json",
+			contentType: QueueContentTypeJSON,
+			val:         "hello",
+			want:        js.ValueOf("hello"),
+		},
+		{
+			name:        "number as json",
+			contentType: QueueContentTypeJSON,
+			val:         42,
+			want:        js.ValueOf(42),
+		},
+		{
+			name:        "bool as json",
+			contentType: QueueContentTypeJSON,
+			val:         true,
+			want:        js.ValueOf(true),
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := tt.contentType.mapValue(tt.val)
+			if (err != nil) != tt.wantErr {
+				t.Fatalf("%s.mapValue() error = %v, wantErr %v", tt.contentType, err, tt.wantErr)
+			}
+			if got.String() != tt.want.String() {
+				t.Errorf("%s.mapValue() = %v, want %v", tt.contentType, got, tt.want)
+			}
+		})
+	}
+}
+
+func TestContentType_mapValue_bytes(t *testing.T) {
+	jsOf := func(b []byte) js.Value {
+		ua := jsutil.NewUint8Array(len(b))
+		js.CopyBytesToJS(ua, b)
+		return ua
+	}
+
+	tests := []struct {
+		name string
+		val  any
+		want js.Value
+	}{
+		{
+			name: "[]byte as bytes",
+			val:  []byte("hello"),
+			want: jsOf([]byte("hello")),
+		},
+		{
+			name: "string as bytes",
+			val:  "hello",
+			want: jsOf([]byte("hello"))},
+		{
+			name: "io.Reader as bytes",
+			val:  bytes.NewBufferString("hello"),
+			want: jsOf([]byte("hello")),
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := QueueContentTypeBytes.mapValue(tt.val)
+			if err != nil {
+				t.Fatalf("%s.mapValue() got error = %v", QueueContentTypeBytes, err)
+			}
+			if got.Type() != tt.want.Type() {
+				t.Errorf("%s.mapValue() = type %v, want type %v", QueueContentTypeBytes, got, tt.want)
+			}
+			if got.String() != tt.want.String() {
+				t.Errorf("%s.mapValue() = %v, want %v", QueueContentTypeBytes, got, tt.want)
+			}
+		})
+	}
+}
+
+func TestContentType_mapValue_map(t *testing.T) {
+	val := map[string]interface{}{
+		"Name": "Alice",
+		"Age":  42,
+	}
+
+	tests := []struct {
+		name        string
+		contentType QueueContentType
+	}{
+		{
+			name:        "json",
+			contentType: QueueContentTypeJSON,
+		},
+		{
+			name:        "v8",
+			contentType: QueueContentTypeV8,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+
+			got, err := tt.contentType.mapValue(val)
+			if err != nil {
+				t.Fatalf("QueueContentTypeJSON.mapValue() got error = %v", err)
+			}
+			if got.Type() != js.TypeObject {
+				t.Errorf("QueueContentTypeJSON.mapValue() = type %v, want type %v", got, js.TypeObject)
+			}
+			if got.Get("Name").String() != "Alice" {
+				t.Errorf("QueueContentTypeJSON.mapValue() = %v, want %v", got.Get("Name").String(), "Alice")
+			}
+			if got.Get("Age").Int() != 42 {
+				t.Errorf("QueueContentTypeJSON.mapValue() = %v, want %v", got.Get("Age").Int(), 42)
+			}
+		})
+	}
+}
+
+type User struct {
+	Name string
+}
+
+func TestContentType_mapValue_unsupported_types(t *testing.T) {
+	t.Run("struct as json", func(t *testing.T) {
+		defer func() {
+			if p := recover(); p == nil {
+				t.Fatalf("QueueContentTypeJSON.mapValue() did not panic")
+			}
+		}()
+
+		val := User{Name: "Alice"}
+		_, _ = QueueContentTypeJSON.mapValue(val)
+	})
+
+	t.Run("slice of structs as json", func(t *testing.T) {
+		defer func() {
+			if p := recover(); p == nil {
+				t.Fatalf("QueueContentTypeJSON.mapValue() did not panic")
+			}
+		}()
+
+		val := User{Name: "Alice"}
+		_, _ = QueueContentTypeJSON.mapValue([]User{val})
+	})
+
+	t.Run("slice of bytes as json", func(t *testing.T) {
+		defer func() {
+			if p := recover(); p == nil {
+				t.Fatalf("QueueContentTypeJSON.mapValue() did not panic")
+			}
+		}()
+
+		_, _ = QueueContentTypeJSON.mapValue([]byte("hello"))
+	})
+}
diff --git a/cloudflare/queues/producer.go b/cloudflare/queues/producer.go
index 972408c..6fa47eb 100644
--- a/cloudflare/queues/producer.go
+++ b/cloudflare/queues/producer.go
@@ -14,6 +14,7 @@ type BatchMessage struct {
 	options *sendOptions
 }
 
+// NewBatchMessage creates a single message to be batched before sending to a queue.
 func NewBatchMessage(body any, opts ...SendOption) *BatchMessage {
 	options := defaultSendOptions()
 	for _, opt := range opts {
@@ -44,6 +45,10 @@ type Producer struct {
 	queue js.Value
 }
 
+// NewProducer creates a new Producer object to send messages to a queue.
+// queueName is the name of the queue environment var to send messages to.
+// In Cloudflare API documentation, this object represents the Queue.
+//   - https://developers.cloudflare.com/queues/configuration/javascript-apis/#producer
 func NewProducer(queueName string) (*Producer, error) {
 	inst := cfruntimecontext.MustGetRuntimeContextEnv().Get(queueName)
 	if inst.IsUndefined() {
@@ -52,6 +57,11 @@ func NewProducer(queueName string) (*Producer, error) {
 	return &Producer{queue: inst}, nil
 }
 
+// Send sends a single message to a queue. This function allows setting send options for the message.
+// If no options are provided, the default options are used (QueueContentTypeJSON and no delay).
+//
+//   - https://developers.cloudflare.com/queues/configuration/javascript-apis/#producer
+//   - https://developers.cloudflare.com/queues/configuration/javascript-apis/#queuesendoptions
 func (p *Producer) Send(content any, opts ...SendOption) error {
 	if p.queue.IsUndefined() {
 		return errors.New("queue object not found")
@@ -72,7 +82,8 @@ func (p *Producer) Send(content any, opts ...SendOption) error {
 	return err
 }
 
-func (p *Producer) SendBatch(messages []*BatchMessage) error {
+// SendBatch sends multiple messages to a queue. This function allows setting options for	each message.
+func (p *Producer) SendBatch(messages []*BatchMessage, opts ...BatchSendOption) error {
 	if p.queue.IsUndefined() {
 		return errors.New("queue object not found")
 	}
@@ -81,6 +92,14 @@ func (p *Producer) SendBatch(messages []*BatchMessage) error {
 		return nil
 	}
 
+	var options *batchSendOptions
+	if len(opts) > 0 {
+		options = &batchSendOptions{}
+		for _, opt := range opts {
+			opt(options)
+		}
+	}
+
 	jsArray := jsutil.NewArray(len(messages))
 	for i, message := range messages {
 		jsValue, err := message.toJS()
@@ -90,16 +109,7 @@ func (p *Producer) SendBatch(messages []*BatchMessage) error {
 		jsArray.SetIndex(i, jsValue)
 	}
 
-	prom := p.queue.Call("sendBatch", jsArray)
+	prom := p.queue.Call("sendBatch", jsArray, options.toJS())
 	_, err := jsutil.AwaitPromise(prom)
 	return err
 }
-
-func (p *Producer) SendJsonBatch(messages ...any) error {
-	batch := make([]*BatchMessage, len(messages))
-	for i, message := range messages {
-		batch[i] = NewBatchMessage(message)
-	}
-
-	return p.SendBatch(batch)
-}
diff --git a/cloudflare/queues/producer_opts.go b/cloudflare/queues/producer_opts.go
index f681874..5d345ae 100644
--- a/cloudflare/queues/producer_opts.go
+++ b/cloudflare/queues/producer_opts.go
@@ -44,8 +44,36 @@ func WithContentType(contentType QueueContentType) SendOption {
 }
 
 // WithDelay changes the number of seconds to delay the message.
-func (q *Producer) WithDelay(d time.Duration) SendOption {
+func WithDelay(d time.Duration) SendOption {
 	return func(o *sendOptions) {
 		o.DelaySeconds = int(d.Seconds())
 	}
 }
+
+type batchSendOptions struct {
+	// DelaySeconds - The number of seconds to delay the message.
+	// Default is 0
+	DelaySeconds int
+}
+
+func (o *batchSendOptions) toJS() js.Value {
+	if o == nil {
+		return js.Undefined()
+	}
+
+	obj := jsutil.NewObject()
+	if o.DelaySeconds != 0 {
+		obj.Set("delaySeconds", o.DelaySeconds)
+	}
+
+	return obj
+}
+
+type BatchSendOption func(*batchSendOptions)
+
+// WithBatchDelay changes the number of seconds to delay the message.
+func WithBatchDelay(d time.Duration) BatchSendOption {
+	return func(o *batchSendOptions) {
+		o.DelaySeconds = int(d.Seconds())
+	}
+}
diff --git a/cloudflare/queues/producer_test.go b/cloudflare/queues/producer_test.go
new file mode 100644
index 0000000..fc00a93
--- /dev/null
+++ b/cloudflare/queues/producer_test.go
@@ -0,0 +1,211 @@
+package queues
+
+import (
+	"errors"
+	"fmt"
+	"syscall/js"
+	"testing"
+	"time"
+
+	"github.com/syumai/workers/internal/jsutil"
+)
+
+func validatingProducer(t *testing.T, validateFn func(message js.Value, options js.Value) error) *Producer {
+	sendFn := js.FuncOf(func(this js.Value, args []js.Value) interface{} {
+		sendArg := args[0] // this should be batch (in case of SendBatch) or a single message (in case of Send)
+		var options js.Value
+		if len(args) > 1 {
+			options = args[1]
+		}
+		return jsutil.NewPromise(js.FuncOf(func(this js.Value, args []js.Value) interface{} {
+			resolve := args[0]
+			go func() {
+				if err := validateFn(sendArg, options); err != nil {
+					// must be non-fatal to avoid a deadlock
+					t.Errorf("validation failed: %v", err)
+				}
+				resolve.Invoke(js.Undefined())
+			}()
+			return js.Undefined()
+		}))
+	})
+
+	queue := jsutil.NewObject()
+	queue.Set("send", sendFn)
+	queue.Set("sendBatch", sendFn)
+
+	return &Producer{queue: queue}
+}
+
+func TestSend(t *testing.T) {
+	t.Run("text content type", func(t *testing.T) {
+		validation := func(message js.Value, options js.Value) error {
+			if message.Type() != js.TypeString {
+				return errors.New("message body must be a string")
+			}
+			if message.String() != "hello" {
+				return errors.New("message body must be 'hello'")
+			}
+			if options.Get("contentType").String() != "text" {
+				return errors.New("content type must be text")
+			}
+			return nil
+		}
+
+		producer := validatingProducer(t, validation)
+		err := producer.Send("hello", WithContentType(QueueContentTypeText))
+		if err != nil {
+			t.Fatalf("Send failed: %v", err)
+		}
+	})
+
+	t.Run("json content type", func(t *testing.T) {
+		validation := func(message js.Value, options js.Value) error {
+			if message.Type() != js.TypeString {
+				return errors.New("message body must be a string")
+			}
+			if message.String() != "hello" {
+				return errors.New("message body must be 'hello'")
+			}
+			if options.Get("contentType").String() != "json" {
+				return errors.New("content type must be json")
+			}
+			return nil
+		}
+
+		producer := validatingProducer(t, validation)
+		err := producer.Send("hello", WithContentType(QueueContentTypeJSON))
+		if err != nil {
+			t.Fatalf("Send failed: %v", err)
+		}
+	})
+}
+
+func TestSend_ContentTypeOption(t *testing.T) {
+	tests := []struct {
+		name                string
+		options             []SendOption
+		expectedContentType string
+		expectedDelaySec    int
+		wantErr             bool
+	}{
+		{
+			name:                "text",
+			options:             []SendOption{WithContentType(QueueContentTypeText)},
+			expectedContentType: "text",
+		},
+		{
+			name:                "json",
+			options:             []SendOption{WithContentType(QueueContentTypeJSON)},
+			expectedContentType: "json",
+		},
+		{
+			name:                "default",
+			options:             nil,
+			expectedContentType: "json",
+		},
+		{
+			name:                "v8",
+			options:             []SendOption{WithContentType(QueueContentTypeV8)},
+			expectedContentType: "v8",
+		},
+		{
+			name:                "bytes",
+			options:             []SendOption{WithContentType(QueueContentTypeBytes)},
+			expectedContentType: "bytes",
+		},
+
+		{
+			name:                "delay",
+			options:             []SendOption{WithDelay(5 * time.Second)},
+			expectedDelaySec:    5,
+			expectedContentType: "json",
+		},
+
+		{
+			name:    "invalid content type",
+			options: []SendOption{WithContentType("invalid")},
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			validation := func(message js.Value, options js.Value) error {
+				gotCT := options.Get("contentType").String()
+				if gotCT != string(tt.expectedContentType) {
+					return fmt.Errorf("expected content type %q, got %q", tt.expectedContentType, gotCT)
+				}
+				gotDelaySec := jsutil.MaybeInt(options.Get("delaySeconds"))
+				if gotDelaySec != tt.expectedDelaySec {
+					return fmt.Errorf("expected delay %d, got %d", tt.expectedDelaySec, gotDelaySec)
+				}
+				return nil
+			}
+
+			producer := validatingProducer(t, validation)
+			err := producer.Send("hello", tt.options...)
+			if (err != nil) != tt.wantErr {
+				t.Fatalf("expected error: %t, got %v", tt.wantErr, err)
+			}
+		})
+	}
+}
+
+func TestSendBatch_Defaults(t *testing.T) {
+	validation := func(batch js.Value, options js.Value) error {
+		if batch.Type() != js.TypeObject {
+			return errors.New("message batch must be an object (array)")
+		}
+		if batch.Length() != 2 {
+			return fmt.Errorf("expected 2 messages, got %d", batch.Length())
+		}
+		first := batch.Index(0)
+		if first.Get("body").String() != "hello" {
+			return fmt.Errorf("first message body must be 'hello', was %s", first.Get("body"))
+		}
+		if first.Get("options").Get("contentType").String() != "json" {
+			return fmt.Errorf("first message content type must be json, was %s", first.Get("options").Get("contentType"))
+		}
+
+		second := batch.Index(1)
+		if second.Get("body").String() != "world" {
+			return fmt.Errorf("second message body must be 'world', was %s", second.Get("body"))
+		}
+		if second.Get("options").Get("contentType").String() != "text" {
+			return fmt.Errorf("second message content type must be text, was %s", second.Get("options").Get("contentType"))
+		}
+
+		return nil
+	}
+
+	var batch []*BatchMessage = []*BatchMessage{
+		NewBatchMessage("hello"),
+		NewBatchMessage("world", WithContentType(QueueContentTypeText)),
+	}
+
+	producer := validatingProducer(t, validation)
+	err := producer.SendBatch(batch)
+	if err != nil {
+		t.Fatalf("SendBatch failed: %v", err)
+	}
+}
+
+func TestSendBatch_Options(t *testing.T) {
+	validation := func(_ js.Value, options js.Value) error {
+		if options.Get("delaySeconds").Int() != 5 {
+			return fmt.Errorf("expected delay 5, got %d", options.Get("delaySeconds").Int())
+		}
+		return nil
+	}
+
+	var batch []*BatchMessage = []*BatchMessage{
+		NewBatchMessage("hello"),
+	}
+
+	producer := validatingProducer(t, validation)
+	err := producer.SendBatch(batch, WithBatchDelay(5*time.Second))
+	if err != nil {
+		t.Fatalf("SendBatch failed: %v", err)
+	}
+}