diff --git a/.gitignore b/.gitignore
index d4d9525..cacc2aa 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 .idea
 .vscode
 .DS_Store
+xtest
\ No newline at end of file
diff --git a/app.go b/app.go
index 8e7fe8f..8dc5930 100644
--- a/app.go
+++ b/app.go
@@ -19,8 +19,6 @@ var (
 
 	regSafePrefix         = regexp.MustCompile("[^a-zA-Z0-9/-]+")
 	regRemoveRepeatedChar = regexp.MustCompile("/{2,}")
-
-	mimePlain = []string{"text/plain"}
 )
 
 type App struct {
@@ -176,7 +174,6 @@ func (a *App) handleHTTPRequest(c *Ctx) {
 				serveError(c, errorHandler)
 			}
 
-			c.writermem.WriteHeaderNow()
 			return
 		}
 		if httpMethod != http.MethodConnect && rPath != "/" {
diff --git a/ctx.go b/ctx.go
index 7ad8566..1b1ea50 100644
--- a/ctx.go
+++ b/ctx.go
@@ -3,7 +3,9 @@ package nf
 import (
 	"bytes"
 	"encoding/json"
+	"errors"
 	"fmt"
+	"github.com/loveuer/nf/internal/sse"
 	"io"
 	"mime/multipart"
 	"net"
@@ -281,7 +283,7 @@ func (c *Ctx) SendString(data string) error {
 
 func (c *Ctx) Writef(format string, values ...interface{}) (int, error) {
 	c.SetHeader("Content-Type", "text/plain")
-	return c.writer.Write([]byte(fmt.Sprintf(format, values...)))
+	return c.Write([]byte(fmt.Sprintf(format, values...)))
 }
 
 func (c *Ctx) JSON(data interface{}) error {
@@ -296,6 +298,23 @@ func (c *Ctx) JSON(data interface{}) error {
 	return nil
 }
 
+func (c *Ctx) SSEvent(event string, data interface{}) error {
+	c.Set("Content-Type", "text/event-stream")
+	c.Set("Cache-Control", "no-cache")
+	c.Set("Transfer-Encoding", "chunked")
+
+	return sse.Encode(c.writer, sse.Event{Event: event, Data: data})
+}
+
+func (c *Ctx) Flush() error {
+	if f, ok := c.writer.(http.Flusher); ok {
+		f.Flush()
+		return nil
+	}
+
+	return errors.New("http.Flusher is not implemented")
+}
+
 func (c *Ctx) RawWriter() http.ResponseWriter {
 	return c.writer
 }
diff --git a/internal/sse/sse-encoder.go b/internal/sse/sse-encoder.go
new file mode 100644
index 0000000..26100e7
--- /dev/null
+++ b/internal/sse/sse-encoder.go
@@ -0,0 +1,106 @@
+package sse
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"reflect"
+	"strconv"
+	"strings"
+)
+
+// Server-Sent Events
+// W3C Working Draft 29 October 2009
+// http://www.w3.org/TR/2009/WD-eventsource-20091029/
+
+const ContentType = "text/event-stream"
+
+var contentType = []string{ContentType}
+var noCache = []string{"no-cache"}
+
+var fieldReplacer = strings.NewReplacer(
+	"\n", "\\n",
+	"\r", "\\r")
+
+var dataReplacer = strings.NewReplacer(
+	"\n", "\ndata:",
+	"\r", "\\r")
+
+type Event struct {
+	Event string
+	Id    string
+	Retry uint
+	Data  interface{}
+}
+
+func Encode(writer io.Writer, event Event) error {
+	w := checkWriter(writer)
+	writeId(w, event.Id)
+	writeEvent(w, event.Event)
+	writeRetry(w, event.Retry)
+	return writeData(w, event.Data)
+}
+
+func writeId(w stringWriter, id string) {
+	if len(id) > 0 {
+		w.WriteString("id:")
+		fieldReplacer.WriteString(w, id)
+		w.WriteString("\n")
+	}
+}
+
+func writeEvent(w stringWriter, event string) {
+	if len(event) > 0 {
+		w.WriteString("event:")
+		fieldReplacer.WriteString(w, event)
+		w.WriteString("\n")
+	}
+}
+
+func writeRetry(w stringWriter, retry uint) {
+	if retry > 0 {
+		w.WriteString("retry:")
+		w.WriteString(strconv.FormatUint(uint64(retry), 10))
+		w.WriteString("\n")
+	}
+}
+
+func writeData(w stringWriter, data interface{}) error {
+	w.WriteString("data:")
+	switch kindOfData(data) {
+	case reflect.Struct, reflect.Slice, reflect.Map:
+		err := json.NewEncoder(w).Encode(data)
+		if err != nil {
+			return err
+		}
+		w.WriteString("\n")
+	default:
+		dataReplacer.WriteString(w, fmt.Sprint(data))
+		w.WriteString("\n\n")
+	}
+	return nil
+}
+
+func (r Event) Render(w http.ResponseWriter) error {
+	r.WriteContentType(w)
+	return Encode(w, r)
+}
+
+func (r Event) WriteContentType(w http.ResponseWriter) {
+	header := w.Header()
+	header["Content-Type"] = contentType
+
+	if _, exist := header["Cache-Control"]; !exist {
+		header["Cache-Control"] = noCache
+	}
+}
+
+func kindOfData(data interface{}) reflect.Kind {
+	value := reflect.ValueOf(data)
+	valueType := value.Kind()
+	if valueType == reflect.Ptr {
+		valueType = value.Elem().Kind()
+	}
+	return valueType
+}
diff --git a/internal/sse/writer.go b/internal/sse/writer.go
new file mode 100644
index 0000000..6f9806c
--- /dev/null
+++ b/internal/sse/writer.go
@@ -0,0 +1,24 @@
+package sse
+
+import "io"
+
+type stringWriter interface {
+	io.Writer
+	WriteString(string) (int, error)
+}
+
+type stringWrapper struct {
+	io.Writer
+}
+
+func (w stringWrapper) WriteString(str string) (int, error) {
+	return w.Writer.Write([]byte(str))
+}
+
+func checkWriter(writer io.Writer) stringWriter {
+	if w, ok := writer.(stringWriter); ok {
+		return w
+	} else {
+		return stringWrapper{writer}
+	}
+}
diff --git a/response_writer.go b/response_writer.go
index 185cddc..62a1fcf 100644
--- a/response_writer.go
+++ b/response_writer.go
@@ -3,6 +3,7 @@ package nf
 import (
 	"bufio"
 	"io"
+	"log"
 	"net"
 	"net/http"
 )
@@ -60,7 +61,7 @@ func (w *responseWriter) reset(writer http.ResponseWriter) {
 func (w *responseWriter) WriteHeader(code int) {
 	if code > 0 && w.status != code {
 		if w.Written() {
-			// todo: debugPrint("[WARNING] Headers were already written. Wanted to override status code %d with %d", w.status, code)
+			log.Printf("[NF] WARNING: Headers were already written. Wanted to override status code %d with %d", w.status, code)
 			return
 		}
 		w.status = code
@@ -102,7 +103,7 @@ func (w *responseWriter) Size() int {
 }
 
 func (w *responseWriter) Written() bool {
-	return w.size != noWritten
+	return w.size != noWritten || w.status != 0
 }
 
 // Hijack implements the http.Hijacker interface.