diff --git a/README.md b/README.md
index 5c6d1f5..1a3c8bc 100644
--- a/README.md
+++ b/README.md
@@ -65,8 +65,8 @@ OPTIONS:
         Namespace(s) to watch for changes. Specify this flag multiple times for each namespace to watch. When not provided all namespaces will be watched.
   -slack-channel string
         The Slack Channel ID for posting updates when uptime checks are mutated.
-  -slack-token string
-        The token required to access the given Slack channel.
+  -slack-webhook-url string
+        The webhook URL required to post messages to the given Slack channel.
   -uptime-provider string
         Name of the (SaaS) uptime monitoring provider to use. (default "mock")
   -zap-devel
diff --git a/cmd/main.go b/cmd/main.go
index 2448b34..ca617d4 100644
--- a/cmd/main.go
+++ b/cmd/main.go
@@ -67,7 +67,7 @@ func main() {
 	var enableHTTP2 bool
 	var namespaces util.SliceFlag
 	var slackChannel string
-	var slackToken string
+	var slackWebhookURL string
 	var uptimeProvider string
 	flag.StringVar(&metricsAddr, "metrics-bind-address", ":8080", "The address the metric endpoint binds to.")
 	flag.StringVar(&probeAddr, "health-probe-bind-address", ":8081", "The address the probe endpoint binds to.")
@@ -81,7 +81,7 @@ func main() {
 	flag.Var(&namespaces, "namespace", "Namespace(s) to watch for changes. "+
 		"Specify this flag multiple times for each namespace to watch. When not provided all namespaces will be watched.")
 	flag.StringVar(&slackChannel, "slack-channel", "", "The Slack Channel ID for posting updates when uptime checks are mutated.")
-	flag.StringVar(&slackToken, "slack-token", "", "The token required to access the given Slack channel.")
+	flag.StringVar(&slackWebhookURL, "slack-webhook-url", "", "The webhook URL required to post messages to the given Slack channel.")
 	flag.StringVar(&uptimeProvider, "uptime-provider", "mock", "Name of the (SaaS) uptime monitoring provider to use.")
 
 	opts := zap.Options{
@@ -159,7 +159,7 @@ func main() {
 		Scheme: mgr.GetScheme(),
 		UptimeCheckService: service.New(
 			service.WithProviderName(uptimeProvider),
-			service.WithSlack(slackToken, slackChannel),
+			service.WithSlack(slackWebhookURL, slackChannel),
 		),
 	}).SetupWithManager(mgr); err != nil {
 		setupLog.Error(err, "unable to create controller", "controller", "IngressRoute")
diff --git a/internal/service/service.go b/internal/service/service.go
index 38d5ea8..f4669b4 100644
--- a/internal/service/service.go
+++ b/internal/service/service.go
@@ -42,10 +42,10 @@ func WithProviderName(provider string) UptimeCheckOption {
 	}
 }
 
-func WithSlack(slackToken string, slackChannel string) UptimeCheckOption {
+func WithSlack(slackWebhookURL string, slackChannel string) UptimeCheckOption {
 	return func(service *UptimeCheckService) *UptimeCheckService {
-		if slackToken != "" && slackChannel != "" {
-			service.slack = NewSlack(slackToken, slackChannel)
+		if slackWebhookURL != "" && slackChannel != "" {
+			service.slack = NewSlack(slackWebhookURL, slackChannel)
 		}
 		return service
 	}
diff --git a/internal/service/slack.go b/internal/service/slack.go
index e47adf1..61a52de 100644
--- a/internal/service/slack.go
+++ b/internal/service/slack.go
@@ -9,25 +9,26 @@ import (
 )
 
 type Slack struct {
-	client    *slack.Client
-	channelID string
+	webhookURL string
+	channelID  string
 }
 
-func NewSlack(token, channelID string) *Slack {
+func NewSlack(webhookURL, channelID string) *Slack {
 	return &Slack{
-		client:    slack.New(token),
-		channelID: channelID,
+		webhookURL: webhookURL,
+		channelID:  channelID,
 	}
 }
 
 func (s *Slack) Send(ctx context.Context, message string) {
-	channelID, timestamp, err := s.client.PostMessageContext(ctx, s.channelID,
-		slack.MsgOptionText(message, false),
-		slack.MsgOptionUsername(model.OperatorName),
-		slack.MsgOptionIconEmoji(":up:"),
-	)
+	err := slack.PostWebhook(s.webhookURL, &slack.WebhookMessage{
+		Channel:   s.channelID,
+		Text:      message,
+		Username:  model.OperatorName,
+		IconEmoji: ":up:",
+	})
 	if err != nil {
 		log.FromContext(ctx).Error(err, "failed to post Slack message",
-			"message", message, "channel", channelID, "timestamp", timestamp)
+			"message", message, "channel", s.channelID)
 	}
 }
diff --git a/internal/service/slack_test.go b/internal/service/slack_test.go
new file mode 100644
index 0000000..16a68d2
--- /dev/null
+++ b/internal/service/slack_test.go
@@ -0,0 +1,38 @@
+package service
+
+import (
+	"context"
+	"os"
+	"testing"
+)
+
+func TestSlack_Send(t *testing.T) {
+	t.Skip() // only for local testing
+	type slackConfig struct {
+		webhookURL string
+		channelID  string
+	}
+	tests := []struct {
+		name    string
+		fields  slackConfig
+		message string
+	}{
+		{
+			name: "test send to some webhook url",
+			fields: slackConfig{
+				webhookURL: os.Getenv("SLACK_WEBHOOK_URL"), // secret!
+				channelID:  os.Getenv("SLACK_CHANNEL_ID"),
+			},
+			message: ":warning:\ntest",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(_ *testing.T) {
+			s := &Slack{
+				webhookURL: tt.fields.webhookURL,
+				channelID:  tt.fields.channelID,
+			}
+			s.Send(context.TODO(), tt.message)
+		})
+	}
+}