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Langfuse alert notifications on your phone.

Get a push notification when a Langfuse alert on latency, cost, errors or scores changes severity, including when it recovers.

Install in Studio See the setup
monitor-alertAIMonitoring
How it works

Three steps to your first push

STEP 01

Install the recipe

One click in Studio gives you a personal webhook URL.

STEP 02

Paste your URL into Langfuse

Add it as a webhook for Alert.

STEP 03

Get a push on your phone

With the text, sound and buttons from the recipe.

Setup

How to set up the Langfuse alert webhook

  1. Click Install in Studio and sign in. The recipe is added to your account and you get a personal webhook URL.
  2. Follow the setup notes below: Alert lives under Prompts > Automations or Project > Alerts.
  3. Choose the Webhook action and paste your webhook URL as the URL.https://••••••••/•••••••• your personal URL, shown after install
  4. Save the automation or alert.
  5. In your Langfuse project, go to **Alerts → New Alert**, set the metric and thresholds, and choose **Webhook** as the notification with the URL above.
  6. Langfuse sends one webhook per severity change (plus optional reminders), so you hear about it when it goes wrong and when it recovers. Alerts are limited per plan (Hobby 2, Core 20, Pro 50).
  7. Langfuse signs each request with `x-langfuse-signature` (HMAC-SHA256), but JustPush doesn't check it yet, so keep your endpoint URL private.
The code

What runs when the webhook arrives

Studio calls handleRequest(request) with the incoming webhook and sends the message it returns. It's yours after install; change anything.

transform.js
1// Langfuse → alert
2// Fires when a Langfuse alert (latency, cost, error rate, scores, …) changes severity.
3// Docs: https://langfuse.com/docs/observability/features/alerts
4
5// Severities: how to label them and how loud to be. PAUSED doesn't push.
6const SEVERITIES = {
7 ALERT: { emoji: "🚨", priority: 1 },
8 WARNING: { emoji: "🟠", priority: 0 },
9 NO_DATA: { emoji: "⚪", priority: 0 },
10 OK: { emoji: "✅", priority: -1 },
11 UNKNOWN: { emoji: "❔", priority: 0 },
12}
13
14// Look a key up in one of the tables above, ignoring inherited names like "toString".
15function pick(table, key, fallback) {
16 return Object.prototype.hasOwnProperty.call(table, key) ? table[key] : fallback
17}
18
19// Only link to real http(s) URLs.
20function link(url, cta) {
21 return typeof url === "string" && /^https?:\/\//.test(url) ? [{ cta, url }] : []
22}
23
24function handleRequest(request) {
25 const body = request.body || {}
26 const alert = body.payload
27
28 // Guard: only monitor alerts, so prompt webhooks on this integration stay quiet.
29 if (body.type !== "monitor-alert" || !alert) {
30 console.log(`Ignoring Langfuse "${body.type ?? "unknown"}" webhook`)
31 return null
32 }
33
34 const severity = pick(SEVERITIES, alert.severity, null)
35
36 if (!severity) {
37 console.log(`Skipping alert with severity "${alert.severity}"`)
38 return null
39 }
40
41 const title = alert.message?.title ?? "Langfuse alert"
42 const text = alert.message?.body ?? `Severity: ${alert.severity}`
43
44 return {
45 title: `${severity.emoji} ${title.charAt(0).toUpperCase()}${title.slice(1)}`,
46 message: text,
47 topic: "Langfuse",
48 priority: severity.priority,
49 buttons: [...link(alert.permalink, "View alert"), ...link(alert.dataPermalink, "View data")],
50 }
51}
Payload

The Langfuse monitor-alert webhook

This is what Langfuse sends to your URL for alert. It is a sample, trimmed to the fields recipes use.

monitor-alert · sample.json
1{
2 "id": "660e8400-e29b-41d4-a716-446655440001",
3 "type": "monitor-alert",
4 "payload": {
5 "view": "observations",
6 "window": "1h",
7 "filters": [],
8 "message": {
9 "body": "avg latency is 1234 ms (threshold: 1000 ms) over the last 1 hour",
10 "title": "avg latency crossed alert threshold"
11 },
12 "severity": "ALERT",
13 "monitorId": "monitor_abc123",
14 "permalink": "https://cloud.langfuse.com/project/proj_xyz789/monitors/monitor_abc123",
15 "projectId": "proj_xyz789",
16 "timestamp": "2026-09-29T10:30:00Z",
17 "toTimestamp": "2026-09-29T10:30:00Z",
18 "fromTimestamp": "2026-09-29T09:30:00Z"
19 },
20 "timestamp": "2026-09-29T10:30:00Z",
21 "apiVersion": "v1"
22}
FAQ

Langfuse alert notifications: questions

Does this work on iPhone and Android?

Yes. Install the JustPush app from the App Store or Google Play and sign in. Every phone signed in to your account gets the notification.

Do I need to write code?

No. Install the recipe in Studio, paste your webhook URL into Langfuse and you are done. The code is there if you want to change the text, the sound or the buttons.

Can I change what the notification says?

Yes. After install the recipe's code is yours. Edit it in Studio and test it against the sample payload before you save.

What does it cost?

JustPush is free for 30 days. After that it's $19.99 a year, or $39.99 once. There is no extra charge for recipes.

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Ready when you are

Langfuse on your phone in two minutes.

Install the recipe, paste one URL, done. Free for 30 days, no credit card required.

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