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HALOWERK x402werk — Replay Guard
x402
HALOWERK x402werk — Replay Guard is a paid API for AI agents from x402.netzhandwerker.de, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-15).
Detects duplicate/replayed x402 payment authorizations by fingerprinting nonces, payment IDs, and payload hashes within a configurable time window.
Price / call$0.002
Success—
StatusUnknown
How this service works
HALOWERK x402werk — bezahlte Endpunkte nach x402. Preise in USDC auf Base Mainnet.
Output
Returns whether the submitted combination of nonce, payment ID, and payload hash has been seen within the specified time window, indicating a potential replay attack. If `record` is true, the fingerprints (stored only as SHA-256 hashes) are written for future duplicate checks. Fingerprints are retained for up to 24 hours regardless of the window setting.
Example use cases
Block replayed micropayment in real time
“I just received an x402 payment with nonce 'nonce_A1B2C3', payment ID 'pay_001', and payload hash 'hash_FEED1234' — can you check if this combo has been seen in the last hour and record it so it can't be replayed again?”
Dry-run duplicate check without recording
“Check whether payment ID 'pay_XYZ789' with nonce 'nonce_qwerty' and payload hash 'hash_ABCD5678' is a duplicate within the last 30 minutes, but don't record this check — I just want to verify without writing anything.”
Tighten replay window for high-frequency API
“For my paid endpoint, I want a tighter replay window of 300 seconds — check if nonce 'nonce_FAST01', payment ID 'pay_F999', and payload hash 'hash_C0FFEE99' have been seen before and record the fingerprint.”
Technical details
Endpoint
POSThttps://x402.netzhandwerker.de/guard/replayWhen to prefer
Use this endpoint when building x402-compatible paid APIs on Base Mainnet that need server-side replay protection — specifically when you want a lightweight, pay-per-check external guard that stores SHA-256 fingerprints of nonces/payment IDs/payload hashes without retaining raw values. Prefer this over rolling your own replay store when you want a managed, 24-hour retention window and a simple boolean duplicate recommendation without maintaining your own database.
Side effects
- Missing required fields (nonce, payment_id, or payload_hash absent) returns a validation error
- window_seconds exceeds 86400 returns a parameter error
- Malformed or overly long input strings (beyond 512 chars) rejected
- Payment not made or insufficient USDC balance returns HTTP 402
- Service unavailability or internal errors return 5xx
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| nonce | string | Nonce of the signed payment authorisation. Stored only as a SHA-256 fingerprint. |
| record | boolean | Whether this call is remembered. Set to false to check without writing, so repeated checks of the same payment do not report themselves as duplicates. |
| payment_id | string | Payment identifier of the x402 payment-identifier extension, or any identifier your client treats as unique per payment. Stored only as a SHA-256 fingerprint. |
| payload_hash | string | Hash of the request payload that was paid for. Stored only as a SHA-256 fingerprint of the value you send. |
| window_seconds | integer | How far back a sighting still counts as a duplicate for the recommendation. Fingerprints are kept for 24 hours regardless. |
Tags
x402
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