Prometheus vs Grafana: What's the Difference? (They're Not Competitors)

"Should I use Prometheus or Grafana?" is one of the most common questions in monitoring — and it reveals a misunderstanding. Prometheus and Grafana aren't alternatives. They do different jobs.

Prometheus collects and stores metrics. Grafana visualizes and alerts on them. Asking "Prometheus or Grafana?" is like asking "PostgreSQL or your admin dashboard?" You probably need both.

What Each Tool Does

How They Work Together

    Your App → exposes /metrics endpoint
     ↓
Prometheus → scrapes /metrics every 15s, stores time-series
     ↓
Grafana → queries Prometheus via PromQL, renders dashboards
     ↓
You → see charts, set alert thresholds, get notified

The typical setup:

1. Your app exposes a /metrics endpoint (using a client library)
2. Prometheus scrapes that endpoint at regular intervals (15s default)
3. Data is stored in Prometheus's time-series database
4. Grafana connects to Prometheus as a data source
5. You build dashboards in Grafana using PromQL queries
6. Alerts trigger when metrics cross thresholds

Can You Use One Without the Other?

Prometheus without Grafana

Yes. Prometheus has a built-in expression browser at :9090/graph and supports alerting via Alertmanager. But the UI is minimal — no saved dashboards, no panels, no annotations. Fine for debugging, not for monitoring at a glance.

Grafana without Prometheus

Yes. Grafana connects to 100+ data sources: InfluxDB, Elasticsearch, CloudWatch, Datadog, PostgreSQL, MySQL, and more. If you're on AWS, you might use Grafana + CloudWatch without Prometheus. If you use Datadog, you can use Grafana as an alternative dashboard layer.

When to Use the Prometheus + Grafana Stack

• You run Kubernetes — Prometheus is the de facto standard for K8s metrics. kube-state-metrics and node-exporter give you full cluster visibility.
• You want zero vendor costs — both are open source, self-hosted.
• You need custom metrics — instrument your app with Prometheus client libraries (Go, Java, Python, Node.js) and track anything.
• Your team knows PromQL — powerful but has a learning curve. If you already know it, this stack is unbeatable.

When NOT to Use This Stack

• You don't want to manage infrastructure. Prometheus needs storage planning, retention policies, and scaling (Thanos/Mimir for long-term). Grafana needs a server. If you want zero ops, use Grafana Cloud (managed) or a SaaS tool.
• You need logs + traces + metrics in one tool. Prometheus only does metrics. You'd need to add Loki (logs) and Tempo (traces) — that's 4+ tools to manage.
• You run a simple Next.js app on Vercel. You can't install Prometheus on Vercel serverless. There's no server to run it on.

Alternatives to the Full Stack

For Next.js on Vercel

If you're running Next.js on Vercel and need API monitoring (not infrastructure metrics), the Prometheus + Grafana stack is overkill. You can't run Prometheus on serverless, and your monitoring need is "are my API routes healthy?" not "what's my node CPU usage?"

Nurbak Watch monitors every API route from inside your server — P50/P95/P99 latency, error rates, instant alerts. No Prometheus, no Grafana, no infrastructure. 5 lines of code, $29/month.

    // instrumentation.ts
import { initWatch } from '@nurbak/watch'

export function register() {
  initWatch({
    apiKey: process.env.NURBAK_WATCH_KEY,
  })
}

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