Source Tracking

The source field lets you distinguish where each signup originates. Sources power the analytics breakdown and help you measure channel performance.

How source resolution works

The SDK resolves the source value in this order:

1. Per-call override - subscribers.create({ source: "..." })
2. URL parameter - ?source= or ?s= query param in the browser URL
3. Instance default - new WaitKit({ source: "..." })
4. Built-in fallback - "landing-page"

// Step 3: instance default
const wk = new WaitKit({
  apiKey: "wk_...",
  projectSlug: "my-project",
  source: "referral",
});

// Step 1: per-call override - uses "partner-page"
await wk.subscribers.create({
  email: "a@example.com",
  source: "partner-page",
});

// Step 3: instance default - uses "referral"
await wk.subscribers.create({ email: "b@example.com" });

// No instance default set - uses "landing-page"
const wk2 = new WaitKit({ apiKey: "wk_...", projectSlug: "my-project" });
await wk2.subscribers.create({ email: "c@example.com" });

URL parameter tracking

In browser environments, the SDK automatically reads ?source= or ?s= from the URL. This lets you tag links to your landing page from different channels:

https://yoursite.com/?source=product-hunt
https://yoursite.com/?s=twitter

This happens before the instance default, so URL parameters override new WaitKit({ source }) but not a per-call override.

Common source values

Viewing source analytics

Open your project dashboard and navigate to the Analytics tab. The Sources chart shows a breakdown of signups by source value, making it easy to compare channel performance.