Junction

Next-generation, Git-native event collection and routing system. A replacement for Adobe Launch and Google Tag Manager built for the modern web.

Why Junction

Tag managers were designed for marketers adding snippets to websites. Junction is designed for engineers building data infrastructure. Events are the primitive — not tags, not rules. Configuration lives in TypeScript files, reviewed in pull requests, deployed through CI/CD.

Config as code. Your tracking config is a TypeScript file in your repo. No web UI, no race conditions, no "who changed that rule in production?"

Consent-first. Events queue until consent is resolved. Destinations only receive events they're allowed to see. DNT and GPC respected out of the box.

Schema validation. Zod contracts enforce event shapes at runtime. Catch typos, missing fields, and type mismatches before they reach your analytics.

Isomorphic. The same collector runs in browsers, Node.js, Deno, Cloudflare Workers, and Bun. Write once, deploy anywhere.

Packages

| Package | Description | |---------|-------------| | @junctionjs/core | Isomorphic collector, consent state machine, Zod validation | | @junctionjs/client | Browser runtime — anonymous IDs, sessions, auto page views | | @junctionjs/astro | Astro v5+ integration — script injection, SSR middleware, View Transitions | | @junctionjs/gateway | WinterCG edge gateway — Cloudflare Workers, Deno, Bun, Vercel Edge | | @junctionjs/destination-amplitude | Amplitude (HTTP API, client + server) | | @junctionjs/destination-ga4 | GA4 (gtag.js, Measurement Protocol, Consent Mode v2) | | @junctionjs/destination-meta | Meta Pixel + Conversions API | | @junctionjs/destination-http | Generic HTTP destination — POST events to any endpoint | | @junctionjs/destination-plausible | Plausible Analytics — privacy-first, consent-exempt | | @junctionjs/debug | In-page debug panel — real-time event flow visibility |

Quick start

npm install @junctionjs/core @junctionjs/client

import { createClient } from "@junctionjs/client";
import { amplitude } from "@junctionjs/destination-amplitude";

const client = createClient({
  name: "my-site",
  environment: "production",
  consent: {
    defaultState: {},
    queueTimeout: 30000,
    respectDNT: true,
    respectGPC: true,
  },
  destinations: [
    {
      destination: amplitude,
      config: { apiKey: "YOUR_KEY", mode: "client" },
      consent: ["analytics"],
    },
  ],
});

// Track events
client.track("product", "viewed", { product_id: "SKU-123", price: 29.99, currency: "USD" });

// Update consent
client.consent({ analytics: true, marketing: false });

// Identify users
client.identify("user-42", { email: "user@example.com" });

Architecture

See docs/ARCHITECTURE.md for the full design document covering data flow, consent semantics, destination plugin interface, and migration paths.

Development

# Install dependencies
npm install

# Build all packages
npm run build

# Run tests
npm test

# Type check
npm run typecheck

# Lint
npm run lint

Writing a destination

Destinations are plain objects with three required methods:

import type { Destination, JctEvent, ConsentState } from "@junctionjs/core";

export const myDestination: Destination<{ apiKey: string }> = {
  name: "my-destination",
  version: "0.1.0",
  consent: ["analytics"],
  runtime: "both",

  init(config) {
    // Load SDKs, validate config
  },

  transform(event: JctEvent) {
    // Convert Junction event to your format. Return null to skip.
    return { name: `${event.entity}_${event.action}`, data: event.properties };
  },

  async send(payload, config) {
    // Send to your service
    await fetch("https://api.example.com/events", {
      method: "POST",
      headers: { "Authorization": `Bearer ${config.apiKey}` },
      body: JSON.stringify(payload),
    });
  },
};

License

MIT