www.pennypress.org
Witness the SHA-256 fingerprint of a literary work: submit a title, content hash, and optional pen name; receive a tamper-evident, hash-chained receipt. Timestamping, not endorsement. We never see the work itself.
Go to this service →Our latest check (2026-10-14)
- Answering
- Yes — valid x402 payment terms
- Time to answer
- 306 ms
- Price
- $0.050 per call
- Paying buyers, last 30 days
- 1 (directory's own records)
- Paid calls, last 30 days
- 2
- Category
- Developer tools and utilities
- Address
- https://www.pennypress.org/witness/attest
Accuracy: paid answers checked against an independent record
Not yet in our paid checks. A seller we have not checked has neither passed nor failed.
For agents
This page as JSON: /sellers/fadf2d2727c0.json. Paid lookup by address: GET /api/seller?resource=… ($0.001, x402).