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

# simulate_invoice

> Simulate payment for a 402-protected resource without executing actual payment

Simulate payment for a 402-protected resource without executing actual payment.
Returns payment requirements and cost estimation without spending funds.
Useful for previewing payment details before committing.

## Signature

```python theme={null}
client.simulate_invoice(api_method: str, api_url: str, api_payload: Optional = None, api_params: Optional = None, api_headers: Optional = None, network: Optional = None)
```

## Parameters

* api\_method: HTTP method (GET, POST, PUT, DELETE, etc.).
* api\_url: Target API URL to simulate access.
* api\_payload: JSON payload for POST/PUT requests.
* api\_params: Query parameters to include.
* api\_headers: Custom headers to send with the request.
* network: Network override for relay mode simulation.

## Returns

Response containing payment requirements and simulation details.

## Raises

* ValueError: If network is incompatible with wallet type or not supported.

## Examples

```python theme={null}
>>> client = HTTPayerClient()
>>> sim = client.simulate_invoice("GET", "https://api.example.com/data")
>>> print(f"Cost: {sim.json()['relayFeeBreakdown']['totalAmount']}")
```