The plain version: what attester.dev sells, what it costs, how refunds work, and where the guarantees end. One page, no legal padding.
attester.dev sells deterministic checks for AI agents, one HTTP call at a time: package and symbol existence lookups against PyPI and npm, version diffs, verification jobs on citations, code, and data, rubric grading, counterparty checks, and MCP manifest integrity checks. Every answer carries an attestation signed by our verifier wallet. The signature proves which key signed which bytes, and that those bytes were not altered after signing. It does not make every conclusion guaranteed correct. Answers are computed from the stated sources at the stated time, and that is the whole of the promise.
Each paid endpoint has a small free quota (per identifier, via the X-Payer header) and the oracle endpoints have a keyless demo tier (25 calls a day per client IP). The live list is /llms.txt; if this page and that file ever disagree, the API response itself is the truth.
| Endpoint | What it does | Price per call |
|---|---|---|
POST /code-research | Cited coding research, citations re-checked | $0.10 |
POST /verify | Verification of citations, code, or data | $0.15 |
POST /judge | Rubric grading with signed score | $0.10 |
POST /watchtower/report | Signed 24h report on a watched x402 service | $0.05 |
POST /spend-check | Pre-payment counterparty verdict | $0.005 |
POST /v1/package/exists | Does this PyPI/npm package exist | $0.002 |
POST /v1/symbol/exists | Does this symbol exist in the package | $0.005 |
POST /v1/symbol/signature | Exact signature at a pinned version | $0.01 |
POST /v1/diff | Symbol-level diff of two versions | $0.02 |
POST /v2/mcp/check | MCP manifest drift check against a pin | $0.01 |
POST /v2/mcp/report | Signed MCP drift history report | $0.05 |
Payment settles per call in USDC on Base through the x402 protocol, with Coinbase's CDP facilitator doing verification and settlement. There are no accounts and no invoices on that rail. The second rail is prepaid credits: you buy a pack from Stripe, claim an att_live_ key once, and calls draw down the balance atomically.
On the credit rail, a failed serve is refunded to your balance automatically (a 4xx or 5xx response reverses the deduction at once). Unused credit is refundable on request to hello@attester.dev. On the x402 rail, settlement is an on-chain transfer and final by nature; a failed serve after a payment attempt comes back as a 503 with a retry window instead of a second charge, and disputes go to the same address.
The service is provided as is. We warrant that each answer was computed from the sources named in its proof block at the time stamped in its attestation. Beyond that we make no warranty, including fitness for a particular purpose. An attestation is evidence about a computation, not a guarantee of the conclusion, and it must not be presented as one. Our total liability for any claim is capped at the price you paid for the call in question.
Do not use the service for anything unlawful, and do not use it to harm the registries, networks, or services the checks touch. Do not present our attestations as guarantees or endorsements to third parties. We may rate-limit or refuse traffic that threatens the service for everyone else. Questions, refund requests, and deletion requests: hello@attester.dev.
Last updated 2026-07-23. See also /privacy, /policy (machine-readable charge and idempotency rules), and /llms.txt.