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Base Chain Transaction Simulator (x402)
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
Price / call$0.003
Success—
StatusUnknown
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.
Example use cases
Pre-flight check for DeFi swap
“Simulate this swap calldata on Base before I execute it — sender is 0xe4be4d0bd82d8e68203deff81f79ede0529f2617, target contract is 0x2626664c2603336E57B271c5C0b26F421741e481, calldata is 0x04e45aaf..., and I want to know the gas cost in USD, whether it'll succeed, and what tokens move.”
Multicall safety review for trading bot
“My trading bot wants to run 3 sequential calls on Base from 0xe4be4d0bd82d8e68203deff81f79ede0529f2617 — can you simulate them all at once and tell me the total gas, any reverts, and all token balance changes before it submits anything?”
Revert diagnosis for failed contract call
“This transaction to 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base keeps failing — sender is 0xe4be4d0bd82d8e68203deff81f79ede0529f2617, calldata is 0xa9059cbb..., can you simulate it and tell me the revert reason?”
Technical details
Endpoint
GEThttps://kr-x402-mvp.kgy5612.workers.dev/v1/crypto/simulate?utm_source=zero.xyzWhen to prefer
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.
Side effects
- 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
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"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
}
}
}
}Tags
x402
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