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x402 Transaction Watch
x402
x402 Transaction Watch is a paid API for AI agents from x402-gateway-production-1f21.up.railway.app, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-10).
Monitors a blockchain transaction by hash and detects state changes, returning a deterministic status snapshot for Base or Ethereum networks.
Price / call$0.003
Success—
StatusUnknown
How this service works
Transaction confirmation watch primitive for autonomous agents. Check whether an EVM transaction is pending, confirmed or reverted and return confirmations plus next-check state. Supply previous_state_hash on later polls to detect status changes without keeping server-side state.
Output
Returns a JSON object with a 'status' field (e.g. 'ready') indicating the current state of the monitored transaction, enabling the caller to detect whether the on-chain state has changed relative to a previously recorded hash.
Example use cases
Confirm DeFi swap completion
“Keep an eye on transaction 0x4f2a...c891 on Base — I just submitted a swap and want to know the moment it moves from pending to confirmed.”
Detect on-chain payment settlement
“Check if this Ethereum transaction 0x7e1d...f302 has settled yet and compare it against the state hash 3a9c...7f44 we recorded earlier so I know if anything changed.”
Agentic payment pipeline verification
“After sending USDC on Base, verify that transaction 0xb88c...0d71 is ready and report whether its current state differs from hash a12e...9c03 I logged previously.”
Technical details
Endpoint
POSThttps://x402-gateway-production-1f21.up.railway.app/agent/transaction-watch?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need deterministic, hash-based change detection for a specific transaction on Base or Ethereum — particularly in agentic pipelines where you need to poll or compare state over time without duplicating logic. Prefer it over generic block explorers when you need a machine-payable, structured API response rather than a human-facing UI, and when you already have a previous state hash to compare against.
Side effects
- Invalid tx_hash format (must be 0x-prefixed 64 hex chars) returns validation error
- Invalid previous_state_hash format returns schema error
- Unsupported network value (not 'base' or 'ethereum') rejected by enum constraint
- Transaction not yet indexed or not found on the specified network
- Payment failure or insufficient USDC balance blocks the x402-gated request
- Network timeout if the RPC node is slow to respond
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"status": "ready"
}
}Tags
x402
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