Configuration

Trackkit can be configured via:

• Programmatic options (recommended, most flexible)
• Environment variables (build-time)
• Runtime injection (e.g. HTML template / CDN)

Runtime and programmatic config always win over build-time env.

Resolution & precedence

When resolving a key like PROVIDER, Trackkit looks in this order:

1. Programmatic options

   Whatever you pass to createAnalytics(opts) / init(opts) is the top source of truth.

2. Runtime injection

   • window.__TRACKKIT_ENV__, e.g. { PROVIDER: "umami" }
   • <meta name="TRACKKIT_PROVIDER" content="umami">

3. Build-time env (suffix after TRACKKIT_)

   • TRACKKIT_PROVIDER
   • VITE_TRACKKIT_PROVIDER
   • REACT_APP_TRACKKIT_PROVIDER

Keys in window.__TRACKKIT_ENV__ should be UPPERCASE and match the suffix after TRACKKIT_ (e.g. PROVIDER, SITE, HOST, QUEUE_SIZE).

Common keys (env + runtime injection)

These keys can be supplied via:

• window.__TRACKKIT_ENV__
• <meta name="TRACKKIT_*">
• TRACKKIT_* / VITE_TRACKKIT_* / REACT_APP_TRACKKIT_* env variables

They map onto the corresponding TypeScript options on the facade.

Key	Type	Description	Default (effective)
PROVIDER	string	Analytics provider (umami, plausible, ga4, noop)	'noop'
SITE	string	Generic provider application identifier	— (aliases WEBSITE / DOMAIN / MEASUREMENT_ID)
WEBSITE / DOMAIN / MEASUREMENT_ID	string	Provider-specific application identifiers	— (either specific or generic identifier required)
HOST	string	Analytics base URL (where applicable)	Provider default (UMAMI_HOST, PLAUSIBLE_HOST, GA_HOST)
QUEUE_SIZE	number	Max in-memory facade queue size	50
DEBUG	boolean (true/false/1/0)	Verbose debug logging	false
AUTO_TRACK	boolean	Enable SPA navigation autotracking	true
DO_NOT_TRACK	boolean	Respect browser’s DNT (set false to ignore)	true
TRACK_LOCALHOST	boolean	Send events from localhost	true (may be overridden by provider metadata)
INCLUDE_HASH	boolean	Include #hash in URLs	false
DOMAINS	string / JSON	Allowed hostnames, e.g. "app.example.com,www.example.com" or ["app.example.com"]	allow all
EXCLUDE	string / JSON	URL substrings to exclude, e.g. "/admin,/debug" or ["/admin"]	none
BATCH_SIZE	number	Max events per facade batch	10
BATCH_TIMEOUT	number (ms)	Max delay before a facade batch flushes	1000
TRANSPORT	string	Transport hint ('auto', 'fetch', 'beacon')	'auto'
DEFAULT_PROPS	JSON	Extra properties merged into events	—
CONSENT	JSON	Initial consent policy (see below)	see Consent defaults

A few important details:

• DOMAINS / EXCLUDE are only applied for pageview events (via the PolicyGate).
• BATCH_SIZE / BATCH_TIMEOUT now back real batching behaviour; they are not reserved knobs.
• TRACK_LOCALHOST can still be influenced by provider metadata (e.g. a provider that never tracks localhost even if you ask).

Build tool prefixes

• Vite: VITE_TRACKKIT_*
• Create React App: REACT_APP_TRACKKIT_*
• Generic/Node: TRACKKIT_*

For Next.js, prefer runtime injection or a custom config loader; the current env reader does not treat NEXT_PUBLIC_* specially.

Runtime injection

Inject config at runtime (e.g. in HTML served by your app or via your CDN):

<script>
  window.__TRACKKIT_ENV__ = {
    PROVIDER: "umami",
    SITE: "your-site-id",
    HOST: "https://analytics.example.com",
    DEBUG: "true",
    AUTO_TRACK: "true",
    QUEUE_SIZE: "100"
  };
</script>

You can also use meta tags for simple keys:

<meta name="TRACKKIT_PROVIDER" content="plausible">
<meta name="TRACKKIT_SITE" content="site-123">
<meta name="TRACKKIT_HOST" content="https://plausible.example.com">

String values like "true" / "false" / "1" / "0" are parsed to booleans where appropriate.

Programmatic init (recommended)

Programmatic config is the “source of truth” and always wins over env/runtime injection.

import { createAnalytics } from 'trackkit';

const analytics = createAnalytics({
  provider: 'plausible',
  site: 'site-123',
  host: 'https://plausible.example.com',
  debug: true,
  autoTrack: true,
  queueSize: 50,
});

You can still use the singleton API if you prefer:

import { init } from 'trackkit';

init({
  provider: 'umami',
  site: 'abc-123',
  host: 'https://analytics.example.com',
});

Both APIs flow through the same normalisation / validation path.

Unified Identifier (site) Trackkit accepts a generic site field as a provider-agnostic identifier. When used, it is mapped automatically:

• Umami → website
• Plausible → site
• GA4 → measurementId

Provider-specific identifiers (website, measurementId, etc.) can still be supplied directly and will override the generic mapping. This enables painless provider switching without rewriting configuration.

Advanced programmatic options

Some options are only expected to be set programmatically (not via env):

• retry
• resilience
• connection
• performance
• detailed consent configuration

These shapes are defined in TypeScript; use your editor’s IntelliSense (or the source files) as the canonical reference.

Retry

Controls backoff and retry for network dispatch.

Defaults (from RETRY_DEFAULTS):

retry: {
  maxAttempts: 3,
  initialDelay: 1000,
  maxDelay: 30000,
  multiplier: 2,
  jitter: true,
  retryableStatuses: [408, 429, 500, 502, 503, 504],
}

Override with:

const analytics = createAnalytics({
  // ...
  retry: {
    maxAttempts: 5,
    initialDelay: 500,
    maxDelay: 60000,
  },
});

Resilience & transports

Controls adblocker detection and transport fallback. Defaults (from RESILIENCE_DEFAULTS):

resilience: {
  detectBlockers: false,
  fallbackStrategy: 'proxy', // 'proxy' | 'beacon' | 'none'
  proxy: undefined,
}

Example with a first-party proxy:

const analytics = createAnalytics({
  // ...
  resilience: {
    detectBlockers: true,
    fallbackStrategy: 'proxy',
    proxy: {
      proxyUrl: '/api/trackkit-proxy',
      token: process.env.TRACKKIT_PROXY_TOKEN,
      headers: { 'X-Trackkit-Source': 'web' },
    },
  },
});

See docs/guides/resilience-and-transports.md for the full story.

Connection & offline

Controls how Trackkit interprets connection health and, if you wire it, how you use offline storage.

Defaults (from CONNECTION_DEFAULTS):

connection: {
  monitor: false,
  offlineStorage: false,
  syncInterval: 30000, // ms
  slowThreshold: 3000, // ms
  checkInterval: 30000, // ms
}

Example:

const analytics = createAnalytics({
  // ...
  connection: {
    monitor: true,
    offlineStorage: true,
    syncInterval: 15000,
    slowThreshold: 5000,
  },
});

The actual connection state / offline behaviour is driven by ConnectionMonitor and OfflineStore; see docs/guides/connection-and-offline.md.

Performance tracking

Controls the lightweight PerformanceTracker.

Defaults (from PERFORMANCE_DEFAULTS):

performance: {
  enabled: false,
  // other fields may exist; see PerformanceOptions in the source
}

Example:

const analytics = createAnalytics({
  // ...
  performance: {
    enabled: true,
  },
});

When enabled and wired in, basic metrics (init time, average processing time, average network latency) become visible via getDiagnostics(). See docs/guides/performance-tracking.md for details.

Consent

The consent system has its own defaults (from CONSENT_DEFAULTS):

consent: {
  initialStatus: 'pending',
  requireExplicit: true,
  allowEssentialOnDenied: false,
  disablePersistence: false,
  storageKey: '__trackkit_consent__',
}

You can override any of these:

const analytics = createAnalytics({
  // ...
  consent: {
    initialStatus: 'denied',
    requireExplicit: true,
    allowEssentialOnDenied: true,
    storageKey: '__myapp_consent__',
  },
});

If you prefer a coarse env-driven approach, you can use a CONSENT JSON env value:

TRACKKIT_CONSENT={"initialStatus":"denied","requireExplicit":true}

Programmatic consent config always wins over env.

Provider-specific notes

Umami

• Required: site (or website)
• Optional: host (TRACKKIT_HOST or host option). Defaults to https://api.umami.is.

Example:

TRACKKIT_PROVIDER=umami
TRACKKIT_SITE=abc-123
TRACKKIT_HOST=https://umami.example.com

Plausible

• Required: site
• Optional: host. Defaults to https://plausible.io.

Example:

TRACKKIT_PROVIDER=plausible
TRACKKIT_SITE=mydomain.com
TRACKKIT_HOST=https://plausible.example.com

GA4

• Required: measurementId (programmatic) or MEASUREMENT_ID (env/runtime).
• Host defaults to GA’s standard endpoints.

Example:

TRACKKIT_PROVIDER=ga4
TRACKKIT_MEASUREMENT_ID=G-XXXXXXX

Programmatic:

createAnalytics({
  provider: 'ga4',
  measurementId: 'G-XXXXXXX',
});

Error handling

Trackkit surfaces typed errors via AnalyticsError with codes like:

• INIT_FAILED
• PROVIDER_ERROR
• NETWORK_ERROR
• QUEUE_OVERFLOW
• INVALID_CONFIG
• INVALID_ENVIRONMENT
• CONSENT_REQUIRED
• POLICY_BLOCKED
• READY_TIMEOUT
• TIMEOUT
• UNKNOWN

You can supply a custom handler:

import { createAnalytics } from 'trackkit';

const analytics = createAnalytics({
  onError: (error) => {
    // error is an AnalyticsError
    console.error('[analytics]', error.code, error.message, {
      provider: error.provider,
      timestamp: error.timestamp,
    });
    // e.g. forward to Sentry / Datadog here
  },
});

If you don’t provide onError, Trackkit logs deduplicated errors via its internal logger.

Debug mode

Enable detailed logs:

createAnalytics({ debug: true });
// or via env
TRACKKIT_DEBUG=true

Debug mode controls:

• verbose queue / consent / navigation logs,
• diagnostics output where enabled,
• provider lifecycle traces.

Use debug: true in development and staging; keep it false in production unless you’re actively investigating an issue.