Node.js

Note: Metrics is in open alpha. Any team can turn it on — open Metrics (opens in a new tab) and select Enable metrics in the onboarding view. Setup details may change before general availability.

The posthog-node (opens in a new tab) SDK includes the posthog.metrics API, so you can record metrics with the same client you use for events and feature flags.

1. 1

   Install posthog-node

   Required

   Terminal

   bashCopy

   npm install posthog-node

   Metrics requires an up-to-date SDK version, so upgrade if you’re on an older release.

2. 2

   Initialize the client

   Required

   Set a service name so metrics from different systems stay easy to tell apart. It’s attached to every series and used by the Metrics UI for filtering.

   JavaScript

   javascriptCopy

   import { PostHog } from 'posthog-node'
   
   const posthog = new PostHog('<ph_project_token>', {
       host: 'https://us.i.posthog.com',
       metrics: { serviceName: 'billing-worker' },
   })

   Use your project token (the same one you use for capturing events), not a personal API key (opens in a new tab).

3. 3

   Record metrics

   Required

   Use the metric type that matches what you’re measuring:

   JavaScript

   javascriptCopy

   // Counters only go up: things you count
   posthog.metrics.count('jobs.processed', 1, { attributes: { queue: 'default' } })
   
   // Gauges go up and down: current values
   posthog.metrics.gauge('queue.depth', 7)
   
   
   

4. 4

   Instrument alongside existing metrics

   Optional

   If your service already records metrics with Prometheus, StatsD, or another system, don’t rip it out. Add the PostHog call next to the existing one, reusing the same metric name and attributes, so both systems chart the same series while you evaluate.

5. 5

   Flush before exit

   Required

   For short-lived processes (cron jobs, CLIs, serverless functions), flush before exiting so the last aggregation window isn’t lost:

   JavaScript

   javascriptCopy

   await posthog.metrics.flush()
   // or, when tearing down the whole client:
   await posthog.shutdown()

6. 6

   Test your setup

   Recommended

   1. Trigger the code path that records a metric
   2. Open Metrics in the PostHog sidebar and pick your metric from the name picker
   3. Data points should appear within a minute of sending

   View your metrics in PostHog (opens in a new tab)

7. Next steps

   Checkpoint

   What you can do with your metrics

   Action	Description
   Why you need metrics (opens in a new tab)	What metrics show you that events and logs don’t
   Getting started guide (opens in a new tab)	Pick the right metric type, add attributes carefully, and chart what matters
   Group and filter	Group by an attribute for one line per value, or filter with key=value chips
   How metrics works

Still have questions?

Ask PostHog AI

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HelpfulCould be better

Samples aggregate in memory and flush as one OTLP data point per series every few seconds, so recording in hot paths is cheap. A burst of 10k count() calls costs one data point on the wire.

Keep attribute values small and bounded: route, status, and plan are good attributes; user IDs, session IDs, and request IDs are not. Every unique combination creates a new series.

Continue with the getting started guide (opens in a new tab)