# Base Chain Transaction Simulator (x402)

> Base Chain Transaction Simulator (x402) is a paid API for AI agents from kr-x402-mvp.kgy5612.workers.dev, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-31).

Simulates one or more Base chain transactions to preview gas costs, token transfers, balance changes, and safety verdict before execution

## Facts

- Endpoint: GET https://kr-x402-mvp.kgy5612.workers.dev/v1/crypto/simulate?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-31
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/base-chain-transaction-simulator-x402-41bb5cc0
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ihrOp5cTRaBPQSHQMCjWW

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 base-chain-transaction-simulator-x402-41bb5cc0
```

Example prompt: Before I send 0.001 USDC from 0xe4be4d0bd82d8e68203deff81f79ede0529f2617 to 0xa587d73489f8f09d1975f1ddbb1c61c93e8fa9d7 on Base, simulate the transaction using the USDC contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 and tell me if it's safe, what gas it'll cost, and what balance changes will happen.

## When to prefer this

Use this endpoint when you need to dry-run a Base chain transaction before committing it onchain — especially for AI trading agents that need safety verdicts, gas estimates, and token flow previews without risking funds. Prefer over on-chain submission when you want to detect reverts, decode function calls, or audit balance changes in advance. The pay-per-call x402 model (no API key) makes it ideal for autonomous agents.

## Known failure modes

- Invalid address format returns 400 validation error
- Malformed calldata hex returns parse error
- Simulation of call that would revert returns success:false with revert_reason populated
- Missing required 'to' param when not using multicall returns 400
- x402 payment failure blocks access with 402 response
- Network congestion on Base may cause simulation timeouts

## How this service works

Pay-per-call crypto microdata for trading/onchain AI agents via x402 (USDC on Base): Base gas, token risk, balances, multi-venue prices, Hyperliquid book/funding, kimchi premium. No API keys.

## Output

Returns a JSON object with: overall success/failure verdict (SAFE_TO_SEND or REVERTED), per-call breakdown (function decoded, gas used, revert reason), total gas used, fee in ETH and USD, list of token transfers with amounts and symbols, balance changes per address, and suggested next endpoints. Block number and chain are also included.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {
      "to": {
       "type": "string",
       "pattern": "^0x[0-9a-fA-F]{40}$",
       "examples": [
        "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"
       ],
       "description": "Target contract or recipient"
      },
      "data": {
       "type": "string",
       "pattern": "^0x([0-9a-fA-F]{2})*$",
       "description": "Calldata (default 0x)"
      },
      "from": {
       "type": "string",
       "pattern": "^0x[0-9a-fA-F]{40}$",
       "examples": [
        "0xe4be4d0bd82d8e68203deff81f79ede0529f2617"
       ],
       "description": "Sender (signer) address"
      },
      "calls": {
       "type": "string",
       "description": "URL-encoded JSON array of up to 5 {to,data,value_eth|value} run in order from the same sender"
      },
      "value_eth": {
       "type": "string",
       "examples": [
        "0.01"
       ],
       "description": "ETH to send, decimal (default 0)"
      }
     },
     "additionalProperties": false
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "from": "0xe4be4d0bd82d8e68203deff81f79ede0529f2617",
  "next": [
   "/crypto/base-gas",
   "/crypto/tx-status?hash="
  ],
  "block": 53272234,
  "calls": [
   {
    "to": "0x833589fcd6edb6e08f4c7c32d4f71b54bda02913",
    "index": 0,
    "success": true,
    "function": "transfer(address,uint256)",
    "gas_used": 45047,
    "revert_reason": null
   }
  ],
  "chain": "base",
  "flags": [],
  "fee_eth": 5e-7,
  "fee_usd": 0.0019,
  "success": true,
  "summary": "1 call succeeds; sender sends 0.001 USDC",
  "verdict": "SAFE_TO_SEND",
  "approvals": [],
  "transfers": [
   {
    "to": "0xa587d73489f8f09d1975f1ddbb1c61c93e8fa9d7",
    "from": "0xe4be4d0bd82d8e68203deff81f79ede0529f2617",
    "token": "0x833589fcd6edb6e08f4c7c32d4f71b54bda02913",
    "amount": 0.001,
    "symbol": "USDC"
   }
  ],
  "gas_used_total": 45047,
  "sender_changes": {
   "USDC": -0.001
  },
  "balance_changes": {
   "0xa587d73489f8f09d1975f1ddbb1c61c93e8fa9d7": {
    "USDC": 0.001
   },
   "0xe4be4d0bd82d8e68203deff81f79ede0529f2617": {
    "USDC": -0.001
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/base-chain-transaction-simulator-x402-41bb5cc0/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from kr-x402-mvp.kgy5612.workers.dev](https://www.zero.xyz/host/kr-x402-mvp.kgy5612.workers.dev/llms.txt)