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 |
Measurement methodology
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:
<script src="https://t.sealmetrics.com/t.js?id=YOUR_ACCOUNT_ID" defer></script>
This script:
- Loads asynchronously (does not block page rendering)
- Tracks the initial pageview automatically
- 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 |
// 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.
Documentation
Getting Started
- Step-by-Step Guide - Complete visual guide from zero to tracking
- Installation - Script tag, content grouping, custom domains
Tracking Events
- Conversions - Tracking purchases, leads, signups
- Microconversions - Tracking funnel steps, engagement events
Advanced
- API Reference - Complete technical reference
- SPA Support - React, Vue, Angular, Next.js integration
- First-Party Setup - Custom domain for tracking
- Tracker v1 to v2: Breaking Changes - Breaking changes and code examples
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