---
title: Analytics
description: First-party web analytics — Vercel Web Analytics, PostHog, or any custom script — wired up from blume.config.ts.
---

Blume injects analytics for you from a single `analytics` block in `blume.config.ts`. Vercel Web Analytics and PostHog are first-class, and a `scripts` escape hatch covers every other provider — Plausible, Fathom, Google Analytics, Umami, and the rest.

Analytics loads in **production builds only**. The scripts are emitted by `blume build`, never by `blume dev`, so local traffic never reaches your dashboards and you don't need a separate "development" project.

:::note
Analytics is opt-in. With no `analytics` block, Blume injects nothing.
:::

## Vercel Web Analytics

Set `vercel: true` to add [Vercel Web Analytics](https://vercel.com/docs/analytics). Blume injects Vercel's first-party script, which is served from your own domain once Web Analytics is enabled for the project in the Vercel dashboard.

```ts blume.config.ts lineNumbers
analytics: {
  vercel: true,
}
```

No keys are needed — the script reports to the project it's deployed under. This only collects data on Vercel deployments, where the `/_vercel/insights` endpoint exists.

## PostHog

Provide your **project API key** to add [PostHog](https://posthog.com). The host defaults to PostHog Cloud US; set `host` for EU Cloud (`https://eu.i.posthog.com`) or a self-hosted instance.

```ts blume.config.ts lineNumbers
analytics: {
  posthog: {
    key: "phc_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx",
    host: "https://us.i.posthog.com", // optional, this is the default
  },
}
```

The project API key is safe to ship to the browser — it's a public, write-only key.

## Custom scripts

Use `scripts` to load any other analytics provider. Each entry renders one `<script>` tag and must set **exactly one** of `src` (external) or `content` (inline).

```ts blume.config.ts lineNumbers
analytics: {
  scripts: [
    // Plausible
    {
      src: "https://plausible.io/js/script.js",
      strategy: "defer",
      attributes: { "data-domain": "example.com" },
    },
    // Fathom
    {
      src: "https://cdn.usefathom.com/script.js",
      strategy: "defer",
      attributes: { "data-site": "ABCDEFG" },
    },
    // An inline snippet
    {
      content: "console.log('analytics ready')",
    },
  ],
}
```

`attributes` is a map of extra HTML attributes (`data-*`, `id`, …) spread onto the tag, and `strategy` adds `async` or `defer` to external scripts.

## Options

| Option | Default | Description |
| --- | --- | --- |
| `vercel` | `false` | Add Vercel Web Analytics (Vercel deployments only). |
| `posthog.key` | — | PostHog project API key. Enables PostHog when set. |
| `posthog.host` | `https://us.i.posthog.com` | PostHog ingestion host (EU Cloud or self-hosted). |
| `scripts[].src` | — | External script URL. Mutually exclusive with `content`. |
| `scripts[].content` | — | Inline script body. Mutually exclusive with `src`. |
| `scripts[].strategy` | — | `async` or `defer` for an external script. |
| `scripts[].attributes` | — | Extra HTML attributes spread onto the `<script>` tag. |

All three can be combined — enable Vercel, PostHog, and custom scripts together. For deploying your built site, see [Deployment](/docs/deployment).