diff --git a/checker.go b/checker.go
index 15003e6..ff805dc 100644
--- a/checker.go
+++ b/checker.go
@@ -32,6 +32,12 @@ func CheckRedirect(policy func(req *http.Request, via []*http.Request) error) Op
 	}
 }
 
+func Debug() Option {
+	return func(c *Checker) {
+		c.debug = true
+	}
+}
+
 // NoRedirect is the alias of the following:
 //
 //	CheckRedirect(func(req *http.Request, via []*http.Request) error {
@@ -59,6 +65,9 @@ type Checker struct {
 	url      string
 	server   *httptest.Server
 	handler  http.Handler
+
+	// debug mode
+	debug bool
 }
 
 // New creates an HTTP Checker for testing with the given handler.
diff --git a/checker_test.go b/checker_test.go
index d351df7..f97419e 100644
--- a/checker_test.go
+++ b/checker_test.go
@@ -95,11 +95,12 @@ func TestNewExternal(t *testing.T) {
 	})
 	ts := httptest.NewServer(mux)
 	defer ts.Close()
-	checker := NewExternal(ts.URL)
+	checker := NewExternal(ts.URL, Debug())
 	require.NotNil(t, checker)
 	assert.Equal(t, DefaultClientTimeout, checker.client.Timeout)
 	assert.True(t, checker.external)
 	checker.Test(t, http.MethodGet, "/some").
+		WithJSON(map[string]string{"key": "value"}).
 		Check().
 		HasStatus(http.StatusOK).
 		HasBody([]byte("hello"))
diff --git a/tester.go b/tester.go
index d11da0b..3a3aa0f 100644
--- a/tester.go
+++ b/tester.go
@@ -3,6 +3,7 @@ package httpcheck
 import (
 	"bytes"
 	"io"
+	"log"
 	"net/http"
 	"net/http/cookiejar"
 
@@ -35,6 +36,19 @@ func (tt *Tester) Check() *Tester {
 	tt.run()
 	defer tt.stop()
 
+	if tt.debug {
+		log.Println("==", tt.request.Method, tt.request.URL)
+		log.Println(">> header", tt.request.Header)
+		body := "nil"
+		if tt.request.Body != nil {
+			b, err := io.ReadAll(tt.request.Body)
+			require.NoError(tt.t, err, "failed to read request body")
+			tt.request.Body = io.NopCloser(bytes.NewReader(b))
+			body = string(b)
+		}
+		log.Println(">> body:", string(body))
+	}
+
 	newJar, _ := cookiejar.New(nil)
 	for name := range tt.pcookies {
 		for _, oldCookie := range tt.client.Jar.Cookies(tt.request.URL) {
@@ -60,6 +74,12 @@ func (tt *Tester) Check() *Tester {
 
 	tt.response = response
 	tt.response.Body = io.NopCloser(bytes.NewReader(b))
+
+	if tt.debug {
+		log.Println("<< status:", tt.response.Status)
+		log.Println("<< body:", string(b))
+	}
+
 	return tt
 }