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Transaction Simulation (Dry-Run Before Signing)
x402
Transaction Simulation (Dry-Run Before Signing) is a paid API for AI agents from x402-services-production.up.railway.app, paid per call via x402, $0.05/call, status unknown (last checked 2026-09-14).
Simulates an EVM transaction to predict whether it will succeed or revert, returning the revert reason, return data, and decoded action — without spending gas.
Price / call$0.05
Success—
StatusUnknown
How this service works
Transaction simulation: will this tx succeed or revert, and why? Returns success/revert reason, return data, and decoded action. Send { chain, to, data, from?, value? }. Dry-run before signing.
Output
Returns whether the transaction would succeed or revert, the revert reason string if it would fail, raw return data, and a decoded human-readable description of the action being performed.
Example use cases
Example prompt
“Before I sign this transaction, can you simulate it on Base to check if it'll succeed or revert? The target is 0xAbCd...1234, the calldata is 0xa9059cbb...0064, sent from 0xMySelf...5678 with 0 value.”
Technical details
Endpoint
POSThttps://x402-services-production.up.railway.app/api/safety/simulateWhen to prefer
Use this endpoint when an AI agent or user wants to pre-flight an EVM transaction before signing or broadcasting it — especially when the calldata is complex, the user is unsure whether a contract call will succeed, or you need to decode what a transaction actually does. Prefer this over just broadcasting when gas safety or user confirmation is important.
Side effects
- Invalid or malformed 'to' address returns a 400 error
- Unsupported chain identifier causes a lookup failure
- Malformed calldata may result in an undecodeable action with partial results
- Simulation against stale state may not reflect real-time chain conditions
- Missing required 'to' field returns a validation error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| torequired | string | 0x target address |
| data | string | 0x calldata |
| from | string | 0x sender |
| chain | string | Chain, default base |
| value | string | Native value in wei |
Tags
x402
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