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Base Transaction Simulator (x402)
x402
Base 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 Ethereum calldata transactions on Base, returning gas usage, token transfers, balance changes, and a SAFE/UNSAFE 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/fail verdict (SAFE_TO_SEND or unsafe), decoded function name, gas used per call and total, fee in ETH and USD, list of token transfers (from/to/amount/symbol), per-address balance changes, approval events, revert reasons if any, current Base block number, and suggested next API endpoints.
Example use cases
Pre-flight DeFi swap safety check
“I'm about to execute a Uniswap swap on Base from my wallet 0xe4be4d0bd82d8e68203deff81f79ede0529f2617 to the router at 0x2626664c2603336E57B271c5C0b26F421741e481 with this calldata. Simulate it first and tell me if it'll succeed, how much gas it burns, and what tokens move.”
Batch transaction preview
“I have 3 Base transactions I want to run in sequence from address 0xe4be4d0bd82d8e68203deff81f79ede0529f2617 — can you simulate all of them together and tell me the total fee in USD and whether any of them revert?”
Suspicious calldata audit
“Someone just sent me a transaction request asking me to call contract 0xabcdef1234567890abcdef1234567890abcdef12 on Base with some calldata I don't recognize. Simulate it from my address 0xe4be4d0bd82d8e68203deff81f79ede0529f2617 and tell me exactly what tokens or approvals it would trigger — is it safe to send?”
Technical details
Endpoint
GEThttps://kr-x402-mvp.kgy5612.workers.dev/v1/simulate?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need to pre-flight a Base chain transaction before committing — especially for DeFi operations, token transfers, or unknown contract calls where you want to verify safety, decode intent, and see exact token movements without spending gas. Prefer over raw eth_call when you want human-readable transfer summaries, USD fee estimates, and a SAFE/UNSAFE verdict in one call. Requires only $0.003 USDC via x402, no API key setup.
Side effects
- Invalid address format returns 400 with schema validation error
- Reverted simulation returns success:false with revert_reason populated
- Malformed calldata hex rejected with parse error
- More than 5 calls in batch array rejected
- x402 payment not provided or insufficient returns 402 Payment Required
- Network timeout on Base RPC node returns 5xx
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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