How to check Meta Pixel event parameters in the browser

Updated September 2026 · 4 min read

The Meta Pixel uses standard events to measure conversions and build audiences. Inspecting their parameters in the browser helps you check the values, currencies, and product data sent by the browser before relying on the Events Manager.

How to see Meta Pixel requests

Open DevTools (F12), go to the Network tab and type facebook.com/tr in the filter.
Trigger a standard event on your site, such as adding a product to the cart or completing a purchase.
Select the request and look at the Payload tab. Meta Pixel parameters are often encoded as cd[...] fields in the query string or form body.

Key parameters to check

Meta’s documentation defines specific parameters for standard events:

ev: the event name, such as Purchase or AddToCart.
cd[value]: the monetary value as a decimal number (e.g., 9.99), without currency symbols.
cd[currency]: a three-letter ISO 4217 code like USD or EUR.
cd[content_ids]: a JSON array of product IDs. cd[contents]: a JSON array of objects with id and quantity, optionally item_price.
cd[num_items]: the quantity of items.

Purchase requires value and currency.

Deduplication with the Conversions API

If you send the same events from the browser and a server (Conversions API), Meta needs to deduplicate them so they only count once.

Look for the eid (Event ID) parameter in the browser request.
For ID-based deduplication, send the Pixel eventID (serialized as eid) as the Conversions API event_id, with the same event name and pixel/dataset, within Meta’s deduplication window. Use a different ID for each distinct event. The browser alone cannot confirm server delivery or deduplication.
Standard events sent multiple times from the browser with identical data without an Event ID can inflate your conversion metrics.

How Tracklint helps

Tracklint is a Chrome DevTools panel that lists the Meta Pixel hits it captures sent to facebook.com/tr, with decoded parameters and product data; consent is assessed using Google consent signals exposed by the page. It checks the captured events against your measurement plan: required parameters and editable rules such as value > 0, currency format, and the presence of content_ids or contents when required by your plan. Its automatic checks flag values that are not numbers, currency codes outside its ISO 4217 list, advanced matching fields that are not in SHA-256 hash format, and standard conversions (purchase, lead and sign-up) sent twice with identical data within 1.5 seconds.

Free: the event inspector, the consent timeline, the automatic checks and a preview of the validation against your plan (the summary, the status of each row and one first finding). Pro: every finding of the validation against your plan, the GA4 vs Meta Pixel comparison and the exports, for US$19/month plus applicable taxes.

Tracklint captures GA4 requests sent to paths ending in /g/collect and Meta Pixel requests sent to facebook.com/tr; it doesn’t cover other endpoints. It checks the requests your browser sends during the journey you record, not processing inside Google Analytics or Meta, server-to-server integrations or legal compliance.

Add to Chrome See what Tracklint checks