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x402 Transaction Safety Guardrail
x402
x402 Transaction Safety Guardrail 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).
Pre-signing safety check that decodes a pending EVM transaction and returns SAFE/CAUTION/DANGER with reasons, detecting sanctioned addresses, drainer patterns, unlimited approvals, and revert risk
Price / call$0.05
Success—
StatusUnknown
How this service works
Pre-sign safety verdict: one call decodes a pending transaction and checks sanctioned counterparties, unlimited-approval/drainer patterns, contract-vs-EOA, and whether it would revert — returning SAFE / CAUTION / DANGER with reasons. Send { chain, to, data, from?, value? }. The must-have guard every signing agent needs.
Output
A JSON object containing a verdict of SAFE, CAUTION, or DANGER, accompanied by an array of human-readable reasons explaining the assessment — covering sanction hits, drainer or unlimited-approval patterns, EOA vs contract status, and whether the transaction would revert on simulation.
Example use cases
Example prompt
“Before I sign this transaction, check if it's safe — it's on Base, sending to 0xAbC123...def456 with calldata 0xa9059cbb...0001 from my wallet 0x1234...5678 with 0 value.”
Technical details
Endpoint
POSThttps://x402-services-production.up.railway.app/api/safety/guardrailWhen to prefer
Use this endpoint as the mandatory pre-signing guard for any AI agent or wallet that executes on-chain transactions — especially when interacting with unfamiliar contracts, token approvals, or DeFi protocols. Prefer it over generic on-chain data lookups when you specifically need a combined safety verdict that covers sanctions screening, drainer detection, and revert simulation in a single call.
Side effects
- Missing required 'to' field returns validation error
- Invalid hex address format causes parse error
- Unknown or unsupported chain identifier may default to Base or return error
- Simulation failure when 'from' is not provided may reduce accuracy
- Contract not verified on chain may limit calldata decoding
- RPC node unavailability on target chain causes timeout
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| torequired | string | 0x target address |
| data | string | 0x calldata (default 0x) |
| from | string | 0x sender (improves simulation) |
| chain | string | Chain, default base |
| value | string | Native value in wei |
Tags
x402
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