# Simulate Asset Changes

> Simulate Asset Changes is a paid API for AI agents from stablecrypto.dev, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-15).

Simulates an Ethereum transaction and returns predicted asset changes before execution

## Facts

- Endpoint: POST https://stablecrypto.dev/api/alchemy/simulation/simulate-asset-changes
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/simulate-asset-changes-1e9b9936
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_lcF5JutroAvYCqGVq8il6

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability simulate-asset-changes-1e9b9936 -d '<json body>'
```

Example prompt: Before I send this swap transaction, can you simulate what asset changes will happen on eth-mainnet? The sender is 0xAbC...123, the recipient contract is 0xDef...456, and the calldata is 0xa9059cbb... with a value of 0x0.

## When to prefer this

Use this endpoint when you need to preview asset changes from a transaction before committing it on-chain, especially for DeFi swaps, token transfers, or smart contract interactions on Alchemy-supported networks like eth-mainnet or base-mainnet. Prefer this over generic RPC passthrough when you specifically need structured asset change output rather than raw simulation data.

## Known failure modes

- Invalid or malformed Ethereum address returns a 400 error
- Unsupported network slug returns an error indicating the network is not recognized
- Simulation failure due to on-chain revert returns an error with revert reason
- Missing required fields (network, from, to) returns a validation error
- Insufficient calldata for complex contract interactions may return incomplete results

## How this service works

Pay-per-request access to CoinGecko, DefiLlama, Alchemy, and Etherscan APIs. No auth, no subscriptions.

## Output

Returns a structured object describing predicted asset changes resulting from the simulated transaction, including token transfers, ETH balance deltas, and NFT movements, without broadcasting anything to the blockchain.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "to": {
   "type": "string",
   "description": "Contract/recipient address"
  },
  "data": {
   "type": "string",
   "description": "Transaction calldata"
  },
  "from": {
   "type": "string",
   "description": "Sender address"
  },
  "value": {
   "type": "string",
   "description": "ETH value in hex"
  },
  "network": {
   "type": "string",
   "description": "Alchemy network slug, e.g. eth-mainnet, base-mainnet"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/simulate-asset-changes-1e9b9936/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from stablecrypto.dev](https://www.zero.xyz/host/stablecrypto.dev/llms.txt)