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Base Transaction Simulator
x402
Base Transaction Simulator 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 blockchain transactions to predict gas usage, token transfers, balance changes, and safety verdict before broadcasting
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 flag and safety verdict (SAFE_TO_SEND or warning), per-call breakdown (function decoded, gas used, revert reason if any), total gas used and fee in both ETH and USD, list of token transfers with amounts and symbols, net balance changes per address, any ERC-20 approval events detected, current block number, and suggested next sibling endpoints to call.
Example use cases
Pre-flight safety check for DeFi trade
“I'm about to call a DEX router on Base to swap 100 USDC for ETH — sender is 0xe4be4d0bd82d8e68203deff81f79ede0529f2617, contract is 0x6131B5fae19EA4f9D964eAc0408E4408b66337b5, with the encoded swap calldata. Simulate it first and tell me the verdict, what tokens leave my wallet, and the estimated fee.”
Batch multi-call simulation
“I need to simulate three chained calls on Base in sequence from 0xe4be4d0bd82d8e68203deff81f79ede0529f2617 — approve USDC, deposit into a vault, then claim rewards. Can you dry-run all three together and show me which ones succeed, how much gas each uses, and the net balance changes?”
Rug / unexpected approval detection
“Someone sent me a transaction to sign on Base — to address 0xDeAdBeEf... with some calldata. Before I sign anything, simulate it from my address 0xe4be4d0bd82d8e68203deff81f79ede0529f2617 and check whether it tries to drain my tokens or set any unexpected approvals.”
Technical details
Endpoint
GEThttps://kr-x402-mvp.kgy5612.workers.dev/crypto/tx-simulate?utm_source=zero.xyzWhen to prefer
Use this endpoint when an AI agent needs to preview exactly what a Base L2 transaction will do — token flows, gas cost, safety — before committing. Prefer it over static gas estimators when you need decoded transfers, balance deltas, and a safety verdict in one call. Also prefer it for batch simulation of up to 5 chained calls in a single request. It requires no API key (pay-per-call via x402 USDC micropayment) making it ideal for autonomous agent workflows.
Side effects
- Invalid address format returns 400 validation error
- Malformed calldata hex returns parse error
- Simulation reverts — revert_reason populated and success=false
- Network congestion may cause delayed simulation response
- Unparseable function selector returns raw calldata without decoded function name
- Payment failure via x402 if insufficient USDC balance returns 402
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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