# ISHOB Transaction Simulator

> ISHOB Transaction Simulator is a paid API for AI agents from api.ishob.com, paid per call via x402, $0.0015/call, status unknown (last checked 2026-10-14).

Dry-run an EVM or Solana transaction to see balance changes, approvals, revert reasons, gas cost, and risk level — without broadcasting it

## Facts

- Endpoint: POST https://api.ishob.com/v1/crypto/simulate-tx?utm_source=zero.xyz
- Price: $0.0015/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/ishob-transaction-simulator-24f6fafb
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_jjpHeQ89XCgjF2hpr41Oa

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 ishob-transaction-simulator-24f6fafb -d '<json body>'
```

Example prompt: Before I sign this swap, simulate it on Base — from 0xABC…123 to 0xDEF…456, calldata 0xa9059cbb…, value 0 — and tell me what tokens leave and enter my wallet, whether any unlimited approvals are granted, and what the risk level is.

## When to prefer this

Use this endpoint when an AI agent or user needs to preview the exact outcome of a blockchain transaction before committing — especially for DeFi interactions, NFT approvals, or unfamiliar contracts. It covers both EVM chains (Ethereum, Base, Arbitrum, Optimism, Polygon, BSC) and Solana in one call, returns USD-denominated values, and explicitly flags dangerous approval patterns and risk levels, making it superior to raw RPC simulation which provides no risk assessment or token USD values.

## Known failure modes

- Unsupported chain returns validation error
- Malformed calldata hex causes simulation failure
- Transaction would revert — revert reason returned in response
- Missing required fields (from/to for EVM, transaction for Solana) returns 400
- Network congestion on the simulated chain may cause timeout
- Invalid base64 Solana transaction returns parse error

## How this service works

Simulate a transaction before signing it: what leaves and enters the wallet (native, ERC-20, NFTs, SPL) with USD values, approvals granted (unlimited / to non-contracts), revert reason, gas and fee, plus a risk level. EVM chains via eth_simulateV1 (raw call: from, to, data, value); Solana via simulateTransaction (base64 transaction, unsigned is fine). Nothing is broadcast.

## Output

A JSON object with success status, list of balance changes (token symbol, amount, direction, USD value), list of approvals granted (flagging unlimited or non-contract recipients), revert reason if the transaction would fail, gas used, and an overall risk level (low/medium/high) with any warnings.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "to": {
   "type": "string",
   "description": "EVM: target address"
  },
  "gas": {
   "type": "string",
   "description": "EVM: optional gas limit"
  },
  "data": {
   "type": "string",
   "description": "EVM: calldata hex (default 0x)"
  },
  "from": {
   "type": "string",
   "description": "EVM: sender address"
  },
  "chain": {
   "enum": [
    "ethereum",
    "base",
    "arbitrum",
    "optimism",
    "polygon",
    "bsc",
    "solana"
   ],
   "type": "string"
  },
  "value": {
   "type": "string",
   "description": "EVM: value in wei (decimal or 0x hex)"
  },
  "transaction": {
   "type": "string",
   "description": "Solana: base64-encoded transaction (legacy or v0; signatures not required)"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "success": true,
  "gas_used": 276293,
  "warnings": [],
  "approvals": [],
  "risk_level": "low",
  "balance_changes": [
   {
    "usd": -24.9,
    "amount": "-0.01",
    "symbol": "ETH",
    "direction": "out"
   },
   {
    "usd": 24.89,
    "amount": "24.894345",
    "symbol": "USDC",
    "direction": "in"
   }
  ]
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/ishob-transaction-simulator-24f6fafb/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.ishob.com](https://www.zero.xyz/host/api.ishob.com/llms.txt)