> ## Documentation Index
> Fetch the complete documentation index at: https://mockulator.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Validation Rules

> Define sophisticated validation rules for headers, query params, and request body fields.

## Operators

| Operator   | Description        |
| ---------- | ------------------ |
| `=`        | Equals             |
| `!=`       | Not equals         |
| `>`        | Greater than       |
| `<`        | Less than          |
| `>=`       | Greater or equal   |
| `<=`       | Less or equal      |
| `regex`    | Regular expression |
| `contains` | Contains substring |

## Field Sources

* **Headers** — Validate HTTP headers like `Authorization` or `Content-Type`
* **Query Parameters** — Validate URL parameters like `?page=1&limit=10`
* **Request Body** — Validate JSON, XML, or form data with dot notation support

## Nested Field Access

Use dot notation to validate nested JSON fields:

```
user.profile.email      → validates email in nested object
order.items.0.price     → validates first item's price
metadata.source.type    → validates deeply nested values
```