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TxSim Decoder API — EVM Simulation & Calldata Decoder
x402
TxSim Decoder API — EVM Simulation & Calldata Decoder is a paid API for AI agents from simulate.cyberwarex.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-02).
Decodes raw EVM calldata into a named function with security risk flags and runs a keyless eth_call preview to determine if a transaction would succeed or revert before signing.
Price / call$0.005
Success—
StatusUnknown
How this service works
Pay-per-call EVM transaction simulation and calldata decoder for agents: decode raw calldata into a named function with security risk flags, and run a keyless eth_call preview to see whether a transaction would succeed or revert before signing. Across base, ethereum, arbitrum, optimism, polygon, bsc. Deterministic JSON, no RPC keys or node infra needed.
Output
A JSON object containing: the decoded function name, signature, and named arguments; a risk assessment with a level (none, caution, or danger) and specific flags; a would_succeed boolean indicating if the eth_call simulation passed; a revert_reason string if it failed; asset_changes (v2, requires tracing RPC); and contextual notes and disclaimers about simulation limitations.
Example use cases
Pre-sign token transfer safety check
“I'm about to sign a USDC transfer on Base — the target is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 and the calldata is 0xa9059cbb000000000000000000000000d8da6bf26964af9d7eed9e03e53415d37aa960450000000000000000000000000000000000000000000000000000000005f5e100. Can you decode what it's doing, check for risk flags, and tell me if it would succeed?”
DeFi swap revert diagnosis
“My swap transaction on Arbitrum keeps failing — the contract is 0x1b02dA8Cb0d097eB8D57A175b88c7D8b47997506 and my calldata is 0x38ed1739... from address 0xAbCd1234...5678. Can you simulate it and tell me the revert reason so I know why it's not going through?”
Suspicious calldata security audit
“Someone sent me a transaction to sign on Ethereum targeting 0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D with calldata 0x095ea7b3... — can you decode exactly what function this is calling and flag any danger or security risks before I approve it?”
Technical details
Endpoint
GEThttps://simulate.cyberwarex.com/simulate?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need a keyless, infrastructure-free way to decode raw EVM calldata and/or simulate a transaction across Base, Ethereum, Arbitrum, Optimism, Polygon, or BSC before signing. Ideal for agents performing pre-sign safety checks without managing RPC nodes or API keys. Prefer this over full tracing RPCs for lightweight decode+simulate needs; use a tracing RPC for full asset-change tracking (v2 feature).
Side effects
- Invalid or malformed 'to' address returns a validation error
- Unsupported chain name returns an enum validation error
- Malformed or unrecognized calldata hex may result in an undecoded response with null decoded fields
- Network or RPC issues for the target chain may cause simulation failures
- Transactions that depend on real-time state (e.g. slippage-sensitive swaps) may show would_succeed=true but revert at broadcast time
- Missing 'to' parameter (required) returns a schema validation error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"to": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"note": "asset-level change tracing requires a tracing RPC key (v2)",
"risk": {
"flags": [],
"level": "none"
},
"chain": "base",
"decoded": {
"args": {
"to": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
"amount": "100000000"
},
"function": "transfer",
"signature": "transfer(address,uint256)"
},
"disclaimer": "Static decode + keyless eth_call preview only. This is not financial advice and not a guarantee: a call that would succeed now can still revert at broadcast time (state changes, slippage, MEV). Always verify before signing.",
"asset_changes": null,
"revert_reason": null,
"would_succeed": true
}
}Tags
x402
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