Data Layer Validator
Validate your data layer object structure and values
How It Works
Paste your data layer object
Copy the JavaScript object from your developer or your site's console and paste it in JSON format.
Run validation
The tool checks structure, data types, null/undefined values, and key naming conventions.
Review the report
See a detailed list of issues, warnings, and recommendations for each field.
Data Layer Validator
What Is Data Layer Validation and Why Does It Matter?
The GTM data layer is the backbone of any modern tag management implementation. Every tag in GTM that needs dynamic data reads that data from the data layer. If the data layer contains errors — null values where strings are expected, misspelled key names, numbers formatted as strings — every downstream tag that depends on those values will produce incorrect or empty data.
Common Data Layer Validation Errors
- Null or undefined values for required fields — transaction_id: null, product_price: undefined.
- Numbers as strings — sending price: "29.99" instead of price: 29.99. GA4 arithmetic fails silently.
- Inconsistent key naming — productId on one page, product_id on another. GTM variables are case-sensitive.
- Missing ecommerce: null before pushes — the previous ecommerce object persists unless explicitly cleared.
Building a Reliable Data Layer Schema
The most reliable data layer implementations start with a written schema — a specification document that defines every event name, every key, its data type, whether it is required or optional, and example values. This schema is shared between the analytics team and the development team before any implementation begins.