x402 Verification API

Pay-per-call URL validator: HTTP status + title per URL. $0.01 USDC Base via x402 (PayAI).

Statistical adjudication for agents: you tried N prompts, models or strategies and kept the best - is the winner real, or the search? Eleven endpoints, each answering one question and each able to answer no. Plus verified web extraction cross-checked three independent ways and confidence-scored. Public tamper-evident attestation chain, refund-backed, no account.

Format and checksum validation for IBAN, EU VAT, Polish NIP/REGON/PESEL and email, pay-per-call via x402. Only $0.001 (0.1 cent) per check, paid via x402 in USDC on Base. POST JSON {"value": "..."}; values are never stored and personal identifiers are masked. Also a remote MCP server (/mcp) and A2A agent (/.well-known/agent-card.json).

A measured verdict on whether an endpoint is actually alive. Every reason carries the source it was read from. Sold per call over x402 on Base: probe ($0.01/call, GET /x402/probe); report ($0.50/call, GET /x402/report); batch ($0.10/call, POST /x402/batch).

Adversarial verification for AI agents: an independent skeptic attempts to refute a claim before the agent acts on it, returning a structured verdict (refuted / supported / inconclusive) with calibrated confidence, findings, and citations. Three tiers: quick reasoning check ($0.03) · single skeptic with live web research ($0.20) · three-skeptic panel with majority vote ($0.75). Every verdict carries an Ed25519-signed receipt verifiable offline against our published key. Accuracy benchmarked on the full public AVeriTeC dev set — 78.2% overall, 95.7% on refuted claims — with method and failures published at secondopinionx402.com/benchmark. Zero-install hosted MCP connector at /mcp; Python client: pip install secondopinion-x402. USDC via x402 on Algorand, Base, and Solana; no accounts, no API keys.

Email inboxes for AI agents, by the hour: an address of your choice, one call waits for a message and returns the code or link. No account, paid per call with x402 stablecoins.

Deterministic trust scoring and monitoring for the x402 ecosystem. 88k+ endpoints tracked 24/7 on Base + Solana: probe reliability, latency, spec compliance, price history, and real on-chain USDC settlement per endpoint. Paid API: per-endpoint trust score with live re-probe, bulk scoring tiers (10-500), endpoint history, similar-endpoint discovery, payment tracing, and 30-day watch subscriptions with webhook/Slack alerts. Free: trust preview, leaderboard, ecosystem report, embeddable badges. Scoring is a deterministic formula - no LLM in the loop, fully explainable.

Rendered desktop/mobile checks for AI-built websites. Quick 0.099 USDC standard, eligible intro 0.019 by quote, Acceptance 0.299 for up to three same-origin pages and ten explicit assertions. GET/HEAD only advertise requirements; POST performs paid checks. No confirmed independent buyers.

KHOTEM is a cryptographic witness for AI agents: seal (SHA-256 commitments), attest, verify, timestamp and audit, plus three paid operational-law documents for agent builders. x402 v2 with EIP-712-ready accepts on Base, Polygon and Solana. Direct on-chain USDC verification — no facilitator, no accounts, no API keys. Pay per request, present the settlement txHash in X-PAYMENT. Machine-readable via OpenAPI, Bazaar discovery extension, skill.md, AGENTS.md and llms.txt.

4-cent x402 health check: hit a PayanAgent catalog endpoint and get live 402/accepts/payTo/uptime evidence as JSON. USDC on Base. No signup.

Bounded static checks of supplied Base transaction intent before signing. No execution simulation or safety guarantee. $1.99 USDC per check via x402.

Pay-per-call EU VAT and e-invoice checks for agents: live VIES VAT-number verification, VAT-number format/checksum validation, Peppol participant lookup, structural EU invoice validation and an e-invoice readiness assessment. 0.01 USDC per call on Base (x402 v2, scheme exact). No account or API key. Machine-readable contract at https://mcp.jithox.com/openapi.json. Validation and readiness only: it does not send invoices and gives no legal or tax advice.

Pay-per-request API for checking submitted unified diffs against a caller-provided acceptance contract. Declared checks include diff structure, path policy, static-safety rules, and literal assertions; the response contract exposes PASS, FAIL, or INSUFFICIENT_EVIDENCE with a verification receipt.

Before you pay an x402 URL: one cent says if it is live or dead. Two cents checks the listed price against the live 402. USDC on Base.

Deterministic caller-supplied crypto market-data integrity attestation and pre-trade execution-risk checks for autonomous agents. No order placement and no market-data resale.

Validate up to 10 email addresses per call: syntax, MX and mail provider, disposable, role and free-provider flags, typo fixes (gmial.com to gmail.com), domain age, SPF and DMARC, with a verdict and a 0-100 score. Keys work on the REST API and the MCP server. Pay per call: $0.006 USDC per call on Base, no account or API key (x402, PayAI facilitator).