Custom Data - Upstack Data

Custom data is any key that isn’t a standard parameter or user data. You choose the name, and it goes in the same object as everything else. Each event page lists examples. Sample payload with custom data of each type:

window._upstack('track', 'purchase', {
  // Standard parameters
  orderId: '10421',
  transactionId: '10421',
  value: 81.17,
  currency: 'USD',
  items: [{ id: '8012345678', name: 'Classic Cotton Tee', price: 34.99, quantity: 2 }],

  // User data
  email: 'jane@example.com',

  // Custom data
  loyaltyTier: 'gold',                       // string
  leadValue: 40,                             // number
  giftOrder: false,                          // boolean
  promoCodes: ['SAVE10', 'FREESHIP'],        // array
  referral: { partner: 'acme', tier: 2 }     // object
});

Where can I use custom data?

This uses the loyaltyTier and leadValue keys from the sample above.

Where	How to use it	Example
PostHog	It arrives as an event property under the same name	Filter a PostHog insight by `loyaltyTier`
Slack messages	Add a placeholder to your message template	`Order from a {{data.loyaltyTier}} member`
Event mapping conditions	Use the key as the condition field	`data.loyaltyTier` equals `gold`, to create a `gold_member_purchase` event
Value formulas	Use the key in a custom formula	`data.leadValue * 0.4`

Which destinations receive custom data?

Only PostHog and Slack. Meta, TikTok, Google Ads, Klaviyo and other ad and email platforms receive standard parameters only. To get a custom value to one of those platforms, use a value formula to send it as the event value, or an event mapping condition to send a separate event.

How do I name custom keys?

Use one style across your events, such as loyaltyTier.
Don’t reuse a standard parameter name for your own data. value always means the event value.
Keep the same key and type on every event. A key that’s a number on one event and a string on another won’t work in a value formula.

Can I put email addresses in custom keys?

No. Use user data, which is hashed before it’s sent to ad platforms. PostHog receives custom keys exactly as you send them.

​Where can I use custom data?

​Which destinations receive custom data?

​How do I name custom keys?

​Can I put email addresses in custom keys?

Where can I use custom data?

Which destinations receive custom data?

How do I name custom keys?

Can I put email addresses in custom keys?