---
title: "Tracker Overview"
description: "Sealmetrics' 1.2 KB gzipped JavaScript tracker: one-line install, no cookies or localStorage, automatic SPA detection, and size comparisons vs GA4."
canonical_url: "https://docs.sealmetrics.com/implementation/tracker"
lang: "en"
date_generated: "2026-10-08T17:47:47.862Z"
source_hash: "c32e1a06bfa07eac26764e282071a3e606c16d164eb6ffd2d70c7cb8a40d9876"
content_type: "implementation"
owner: "engineering"
llm_priority: "critical"
source_file: "implementation/tracker/index.mdx"
publisher: "Sealmetrics"
---

# Tracker Overview

Canonical page: https://docs.sealmetrics.com/implementation/tracker

Ultra-lightweight JavaScript tracker for collecting analytics data.

| Specification | Value |
|---------------|-------|
| Size (minified) | ~2,228 bytes |
| Size (gzipped) | **~1,227 bytes** |
| Dependencies | None (vanilla JavaScript) |
| Cookies | None |
| localStorage | None |
| sessionStorage | None |
| Browser support | Chrome 60+, Firefox 55+, Safari 11.1+, Edge 79+ |
| Accounts per page | One |

## Size Comparison

### Privacy-First Analytics

| Platform | Minified | Gzipped | vs Sealmetrics |
|----------|----------|---------|----------------|
| **Sealmetrics** | 2.2 KB | **1.1 KB** | — |
| Plausible | 3.0 KB | 1.3 KB | ~same |
| Fathom | 6.2 KB | 1.9 KB | 1.5x heavier |
| Simple Analytics | 7.5 KB | 3.8 KB | 3.1x heavier |

### Enterprise Analytics

| Platform | Minified | Gzipped | vs Sealmetrics |
|----------|----------|---------|----------------|
| **Sealmetrics** | 2.2 KB | **1.1 KB** | — |
| Mixpanel | 91 KB | 29.8 KB | **23x** heavier |
| PostHog | 176 KB | 56.4 KB | **43x** heavier |
| Matomo | 224 KB | 65.2 KB | **50x** heavier |
| Google Analytics 4 | 365 KB | 129.6 KB | **99x** heavier |
| Adobe Analytics | 695 KB | 150.7 KB | **117x** heavier |

**Info:**
All sizes measured in February 2026 by downloading production scripts directly from each vendor's CDN. Gzipped sizes calculated using standard gzip compression. Adobe Analytics measured from a real-world implementation (includes Adobe Launch + extensions).

## Quick Start

Add one line to your HTML:

```html
<script src="https://t.sealmetrics.com/t.js?id=YOUR_ACCOUNT_ID" defer></script>
```

This script:
1. Loads asynchronously (does not block page rendering)
2. Tracks the initial pageview automatically
3. Detects SPA navigation automatically (React, Vue, Angular, Next.js)

## API

| Function | Purpose | Example |
|----------|---------|---------|
| `sealmetrics()` | Manual pageview | `sealmetrics()` |
| `sealmetrics({ group })` | Pageview with content grouping | `sealmetrics({ group: 'blog' })` |
| `sealmetrics.conv(type, amount)` | Conversion | `sealmetrics.conv('purchase', 99.99)` |
| `sealmetrics.conv(type, amount, props)` | Conversion with properties | `sealmetrics.conv('purchase', 99.99, { currency: 'EUR' })` |
| `sealmetrics.micro(type)` | Microconversion | `sealmetrics.micro('add_to_cart')` |
| `sealmetrics.micro(type, props)` | Microconversion with properties | `sealmetrics.micro('add_to_cart', { product_id: 'SKU-123' })` |

## Global Variables

The tracker exposes three identical global variables:

| Variable | Recommendation |
|----------|----------------|
| `sealmetrics` | Recommended (unique, no conflicts) |
| `sm` | Short form |
| `_sm` | Backup if others conflict |

```javascript
// All three work identically:
sealmetrics.conv('purchase', 99.99);
sm.conv('purchase', 99.99);
_sm.conv('purchase', 99.99);
```

## Privacy

The tracker does not collect or store:
- Cookies
- IP addresses (checked in flight against a public list of automated-traffic IPs and your IP exclusions, then discarded — never stored)
- Personal identifiable information
- Form inputs
- User credentials
- localStorage or sessionStorage data

Session identification is cookieless: the tracker computes, in the browser, a hash of standard device characteristics (no canvas fingerprinting) that is never written to the device and is re-keyed on the server with a daily salt, so nothing stored can link a device across days. See [What We Track](/security-privacy/what-we-track).

## Documentation

### Getting Started

- [**Step-by-Step Guide**](/implementation/tracker/step-by-step-guide) - Complete visual guide from zero to tracking
- [Installation](/implementation/tracker/installation) - Script tag, content grouping, custom domains

### Tracking Events

- [Conversions](/implementation/tracker/conversions) - Tracking purchases, leads, signups
- [Microconversions](/implementation/tracker/microconversions) - Tracking funnel steps, engagement events

### Advanced

- [API Reference](/implementation/tracker/api-reference) - Complete technical reference
- [SPA Support](/implementation/tracker/spa-support) - React, Vue, Angular, Next.js integration
- [First-Party Setup](/implementation/tracker/first-party) - Custom domain for tracking
- [Tracker v1 to v2: Breaking Changes](/implementation/tracker/migration-from-v1) - Breaking changes and code examples