---
title: "Event Properties"
description: "Attach custom data to conversions and microconversions for detailed analysis."
canonical_url: "https://docs.sealmetrics.com/implementation/custom-properties/event-properties"
lang: "en"
date_generated: "2026-08-12T08:27:36.924Z"
source_hash: "a1285a96de553d9bf21e00da329619886e55904b5fd052172828c0ffedcd742d"
content_type: "implementation"
owner: "engineering"
llm_priority: "critical"
source_file: "implementation/custom-properties/event-properties.mdx"
publisher: "Sealmetrics"
---

# Event Properties

Canonical page: https://docs.sealmetrics.com/implementation/custom-properties/event-properties

Event properties let you attach custom data to conversions and microconversions for deeper analysis.

## How Event Properties Work

Properties are sent with each event and stored alongside it:

```
Event: add_to_cart (microconversion)
├── Standard fields (automatic)
│   ├── timestamp: 2024-01-15T14:32:00Z
│   ├── page_url: /products/widget
│   ├── device: mobile
│   └── country: ES
│
└── Custom properties (you define)
    ├── product_id: SKU-123
    ├── product_name: Widget Pro
    ├── price: 49.99
    └── category: electronics
```

## Adding Properties to Events

### Conversions

Pass properties as the third parameter to `sealmetrics.conv()`:

```javascript
sealmetrics.conv('purchase', 149.99, {
  product_category: 'electronics',
  payment_method: 'credit_card',
  shipping_method: 'express',
  coupon_code: 'SAVE10',
  is_gift: 'false',
  items_count: '3'
});
```

### Microconversions

Pass properties as the second parameter to `sealmetrics.micro()`:

```javascript
sealmetrics.micro('add_to_cart', {
  product_id: 'SKU-123',
  quantity: '2',
  from_wishlist: 'true'
});
```

### Non-Monetary Conversions

Use `0` as the amount for leads, signups, and other non-monetary goals:

```javascript
sealmetrics.conv('lead', 0, {
  form_name: 'contact',
  source: 'homepage'
});
```

## Common Property Patterns

### Product Properties

```javascript
sealmetrics.micro('add_to_cart', {
  // Identification
  product_id: 'SKU-12345',
  product_name: 'Wireless Headphones',
  product_variant: 'Black',

  // Categorization
  category: 'Electronics',
  subcategory: 'Audio',
  brand: 'Sony',

  // Pricing
  price: '149.99',
  original_price: '199.99',
  discount_percent: '25',

  // Inventory
  in_stock: 'true',
  stock_level: 'low'
});
```

### Content Properties

```javascript
sealmetrics.micro('article_read', {
  // Identification
  content_id: 'article-456',
  content_title: 'How to Choose Headphones',

  // Categorization
  content_type: 'article',
  category: 'buying-guides',
  tags: 'audio,headphones,wireless',

  // Metadata
  author: 'jane-smith',
  publish_date: '2024-01-10',
  word_count: '1500',
  read_time: '7',

  // Features
  has_video: 'true',
  has_gallery: 'true'
});
```

### User Action Properties

```javascript
sealmetrics.micro('begin_checkout', {
  // Action context
  action_location: 'cart_page',

  // State before action
  items_in_cart: '3',
  cart_value: '249.99',

  // Action details
  selected_shipping: 'express',
  estimated_delivery: '2024-01-18'
});
```

## Using Properties in Reports

### Filtering

Filter reports by property values:

```
Traffic Report
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Filters:
+ product_category equals "electronics"
+ payment_method equals "credit_card"

Showing: Credit card purchases in Electronics
```

### Breaking Down

Break down metrics by property:

```
Conversions by Payment Method
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

payment_method    Conversions    Revenue      AOV
──────────────────────────────────────────────────
credit_card            234      €35,100    €150
paypal                  89      €11,570    €130
apple_pay               67       €9,380    €140
bank_transfer           23       €4,600    €200
```

## Data Types

### All Values Are Strings

Sealmetrics stores all property values as strings:

```javascript
// Recommended: use strings explicitly
sealmetrics.conv('purchase', 99.99, {
  price: '49.99',
  quantity: '2',
  is_sale: 'true',
  discount_percent: '25'
});
```

Numbers and booleans are automatically converted to strings, so both forms work:

```javascript
// Also works (auto-converted)
sealmetrics.conv('purchase', 99.99, {
  price: 49.99,
  quantity: 2,
  is_sale: true
});
```

## Dynamic Properties

### From Data Layer

Read from an existing data layer:

```javascript
sealmetrics.conv('purchase', dataLayer[0].orderTotal, {
  category: dataLayer[0].productCategory,
  brand: dataLayer[0].brand
});
```

### From DOM

Read from page elements:

```javascript
document.querySelector('.add-to-cart').addEventListener('click', function() {
  sealmetrics.micro('add_to_cart', {
    product_id: this.dataset.productId,
    product_name: this.dataset.productName,
    price: this.dataset.price
  });
});
```

### From URL Parameters

```javascript
var params = new URLSearchParams(window.location.search);

sealmetrics.micro('search', {
  search_query: params.get('q') || '',
  sort_by: params.get('sort') || 'relevance',
  page_number: params.get('page') || '1'
});
```

## Debugging Properties

### Inspect the network request

The tracker does not have a console debug mode. To verify what is being sent, open your browser's DevTools, go to the **Network** tab, and filter for requests to `t.sealmetrics.com/event` (sent via `sendBeacon` or `fetch`). The request body contains a single `d` field with the URL-encoded JSON payload — your properties are under the `x` key. A successful request returns `204 No Content`.

### Verify in Dashboard

Check properties arrived correctly:

1. Go to **Reports**
2. Find your event
3. Click to see properties

## Troubleshooting

### Properties Not Appearing

1. **Check property names** — Use alphanumeric characters and underscores
2. **Confirm the hit arrived** — the **Last hit** timestamp on the **Overview** report updates within seconds of a tracked visit. If it doesn't move, the event never arrived — see [Data Delay](/troubleshooting/data-delay)
3. **Inspect the network request** — Check the DevTools Network tab for the request to `t.sealmetrics.com/event` and confirm your properties appear under the `x` key in the payload

### Wrong Values

1. **Check data types** — All values are stored as strings
2. **Check encoding** — Ensure valid UTF-8 characters
3. **Check total payload size** — The `/event` request body is capped at 15 KB; if your event (including all properties) exceeds that, the whole event is dropped

### Missing on Some Events

1. **Check conditional logic** — Properties only sent when defined
2. **Check timing** — Ensure data is available when event fires
3. **Check errors** — Look for console errors before the tracking call