nsgoods

curl https://signals.nsgoods.org/signals/preview
→ {"pair":"BTC/USD","signal":"…","signed_by":"0x…"}

curl https://trust.nsgoods.org/agent-trust/preview
→ {"agent":…,"score":…,"components":{…},"signed_by":"0x…"}

curl https://regime.nsgoods.org/provable/head
→ {"count":1887,"head":{"regime":"RISK_OFF",…}}

curl "https://schema.nsgoods.org/extractability/preview?url=https://example.com"
→ {"score":…,"grade":"…"}

curl "https://solar.nsgoods.org/solar-legality/preview?state=california"
→ {"state":"california","legal_status":"…"}

curl "https://trust.nsgoods.org/screen/preview?address=0x…&chain=base"
→ {"malicious":…,"sanctioned":…,"hard_flags":[…],"soft_flags":[…],"sources":[…],"screening_verdict":"…","signed_by":"0x…"}

OFAC sanctions — Chainalysis on-chain oracle (EVM)
malicious-address — GoPlus (EVM + Solana)

Solana mainnet · USDC (SPL) · gasless (facilitator feePayer)
payTo 35tCuyL3E7M88jfhTeEaRxhrbuKFyQLWgxJQyf5QcLLe

curl "https://sanctions.nsgoods.org/screen/preview"
→ {"preview":true,"demo_address":"0x19aa…4dff","input_ignored":false,"sanctioned":true,"matched_label":"ETH","verdict":"deny","sdn_snapshot_at":"…","signed_by":"0x57fF…"}

OFAC SDN exact-address match (live counts: sanctions.nsgoods.org/health)
Negative-evidence only — deny, or "no SDN match" (≠ safe). No heuristic/GoPlus layer.

Verifying the signature on /screen/preview. The preview response adds four fields after signing: preview, demo_address, input_ignored, note. Strip all four, plus signature and signed_by, before you verify. The paid /screen response adds nothing after signing, so there you strip only signature and signed_by. Canonicalise the remainder as json.dumps(sort_keys=True, separators=(',',':'), ensure_ascii=True) — non-ASCII is therefore \uXXXX-escaped — and recover with EIP-191 personal_sign (the Ethereum signed-message prefix).

Base (USDC, payTo 0xc87a06…5EF990) or Solana (USDC-SPL, payTo 35tCuyL3…) — Base first

curl "https://payable.nsgoods.org/payable/preview"
→ {"schema_version":2,"verdict":"PAYABLE","payable_networks":["solana:5eykt…"],"options":[{"network":"solana:5eykt…","verdict":"PAYABLE","detail":{"ata_exists":true,"token_program":"spl"}}],"preview":true,"demo_resource":"https://sanctions.nsgoods.org/screen","signed_by":"0x41Fb…"}

Reachable + well-formed 402 + (Solana) destination-ATA existence. Derive ATA = find_program_address([payTo, tokenProgram, mint], ATokenGP…); ≤3 RPC calls. Every response signed.

Recover the signer over the canonical JSON with signature + signed_by removed; recover == signed_by. On /payable/preview strip the four post-sign fields first (preview, demo_resource, input_ignored, note). Canonicalise as json.dumps(sort_keys=True, separators=(',',':'), ensure_ascii=True) — non-ASCII is \uXXXX-escaped — and recover with EIP-191 personal_sign (the Ethereum signed-message prefix).

Base (USDC, payTo 0xc87a06…5EF990). The subject verified is on Solana; the paid call settles on Base.

VERIFIED — finalized and every asserted field matches (amount is the exact net credited to payee at token-account level)
REFUTED — finalized but ≥1 field mismatch (per-field breakdown shown)
UNCONFIRMED — found, not yet finalized · NOT_FOUND — not seen as of the searched slot

curl "https://x402.nsgoods.org/settle/preview"
→ {"schema_version":"settle_v1","verdict":"VERIFIED","fields":[{"field":"amount","asserted":"415803","observed":"415803","match":true}],"commitment":"finalized","slot":443406404,"signer":"0x57fF…","signature":"0x…","preview":true}

Strip the post-sign fields (preview, note); remove envelope.signature (keep signer); canonicalise json.dumps(sort_keys=True, separators=(',',':'), ensure_ascii=True) and recover with EIP-191 personal_sign; recover == signer.

payability — can the address settle (transfer simulation)
sanctions — OFAC SDN exact-address screen
trust — ERC-8004 reputation (DATA / NO_DATA)
Each is signed on its own; no aggregate score, only a components_evaluated count.

Base (USDC, payTo 0xc87a06…5EF990).

curl "https://x402.nsgoods.org/preflight/preview"
→ {"schema_version":"preflight_v3","components":[{"component":"payability","verdict":"PAYABLE"},{"component":"sanctions","verdict":"CLEAR"},{"component":"trust","verdict":"NO_DATA"}],"components_evaluated":3,"envelope":{"signer":"0x57fF…","signature":"0x…"},"preview":true}

Strip the post-sign fields (preview, note); verify each component (remove component_digest + component_signature, canonicalise, sha256 == digest, recover EIP-191 to signer) and the envelope (remove envelope.signature, keep signer, recover).

endpoint_unreachable / endpoint_recovered
verdict_degraded / verdict_restored
payto_changed / networks_changed / asset_changed
self_inconsistent_402_detected
listing_disappeared_from_catalog (weak)
Each alert carries, verbatim, what it does NOT mean.

One paid x402 call = 30-day subscription for one endpoint.
Free tier: one endpoint per verified channel (email or webhook).
Verification (email code / webhook nonce) required before any alert.

Base (USDC, payTo 0xc87a06…5EF990).

Every alert is EIP-191-signed by 0x57fF…350c: remove digest + signature, canonicalise (sorted keys, compact separators, non-ASCII escaped), sha256 == digest, recover to signer.

OFAC SDN · UN Consolidated · EU FSF (official, public token) · UK Sanctions List (FCDO)
Each list: matched/clear + that list's version date, in one signed body.
list_health: a stale or unavailable feed is reported, never a silent clear.
Headline verdict keeps /screen semantics — deny only on an OFAC SDN match.

USDC on Base (payTo 0xc87a06…5EF990) or Solana (payTo 35tCuyL3…QcLLe).

Signed by 0x57fF…350c. Paid response: strip signature + signed_by. /screen-multi/preview: also strip preview, demo_address, input_ignored, note. Canonicalise (sorted keys, compact separators, non-ASCII escaped) and recover with EIP-191 personal_sign; recover == signed_by.