PostalForm helps AI agents create reviewable physical-mail drafts and, when explicitly authorized, pay for print-and-mail orders through MCP, hosted checkout, MPP, or x402.

GPT-5.6 Luna Standard chat is $0.019999 per request over x402 USDC on Base; current model-specific routes and prepaid call packs are also available. Market benchmark: the latest local x402.direct sample found AI-like listing prices with p25 around $0.01 and median around $0.03 per call; this gateway publishes GPT-5.6 Luna Standard at $0.019999 and model-specific prices at /pricing.json. GPT-5.6 Luna Standard is $0.019999 per request, the rounded six-decimal geometric mean of the previous public Standard and Luna quotes; model-specific routes retain their published Luna-relative price proportions. Service hub: https://gpt55.558686.xyz/x402/service and https://gpt55.558686.xyz/x402/service.json. Discovery assets: https://gpt55.558686.xyz/openapi.json, https://gpt55.558686.xyz/llms.txt, https://gpt55.558686.xyz/tools.json, https://gpt55.558686.xyz/apis.json, https://gpt55.558686.xyz/directory-submission.json. Agent and MCP metadata: https://gpt55.558686.xyz/.well-known/agent-card.json, https://gpt55.558686.xyz/.well-known/ai-catalog.json, https://gpt55.558686.xyz/.well-known/mcp/server-card.json, https://gpt55.558686.xyz/server.json. Integration hub: https://gpt55.558686.xyz/integrations and https://gpt55.558686.xyz/integrations.json. Best for agents that need one-call GPT-5.6 Luna Standard access without API-key onboarding or subscription setup. Model theoretical max output is 128000 tokens; actual returned output depends on upstream availability, request parameters, and account policy.

Agent-only discovery for fresh, exact-commit Agent Skill validation. Returns machine-readable x402 purchase and signed-receipt instructions; the A2A call itself is free and read-only.

Protocol-neutral market intelligence for the AI agent economy. Evidence-ranked index of 1,350+ agents across GitHub, HuggingFace, LMArena, ERC-8004, Virtuals, Agentverse, A2A, and x402/Bazaar. Ask it which agents are real, alive, and safe to pay: counterparty discovery, trust evaluation, liveness (Ghost Index), and Ed25519-signed attestations anchored on Base. Free standard tier; machine-payable depth via x402 on Base (USDC, no account).

Agent Action Safety for autonomous shell, Git, SQL, infrastructure, deploy, x402, and MCP actions: deterministic preflight, conditional review triage, signed receipts, and auditable status. Finance and validation endpoints remain available as utility tools.

Visual agent flows published as machine-callable endpoints. Current capabilities are listed per agent with x402 payment discovery and A2A descriptors.

Modular MCP server exposing stateless tools and reasoning agents. All endpoints are pay-per-call via x402 USDC micropayments on Base. Query /catalog for machine-readable pricing and input schemas.

Machine-actionable market information API for AI agents. Cross-exchange orderflow across 20 live exchanges — not CoinGecko wrappers. /data returns 16 reliable fields at $0.20 for your own models. /analyze/market and /analyze/orderflow are data-only (fast, no LLM latency). /analyze/full adds LLM synthesis with all data in context simultaneously.

Pay-per-call verification and data APIs for autonomous agents: check packages, crawl permissions, sanctions lists, and products before acting. x402 v2, USDC on Base. No API keys, no signup — payment is the authentication.

Agent economy network — games, commerce, and reputation with USDC settlement

Domain-agnostic x402 capability chassis by IntuiTek¹. 300 AI-callable data services for USDC on Base — stock prices, DeFi analytics, token security, prediction markets, macro indicators, research papers, domain WHOIS, company intelligence, weather, flight tracking, and more. MCP interface at /mcp — no wallet, no API keys.

Brazil corporate decision infrastructure for autonomous agents. Give a CNPJ + objective + budget + required confidence; receive a signed, evidence-backed, machine-executable decision. Paid per request via x402.

Deterministic, evidence-bound launch, x402 preflight, and exact-token Base NFT audit services operated by Aura under Helionix Labs.

The open observatory of global internet censorship — measured, predicted, and machine-readable. 2.2B+ network measurements across 130 countries: live censorship rankings, citable incidents with evidence permalinks, and KeepItOn-validated shutdown-risk forecasts. Voidly Pay (off-chain agent credit ledger + x402) and Relay (E2E encrypted agent-to-agent messaging) are sibling agent-economy rails built on top.

The trust layer for agent payments (x402 on Base). Four services on one endpoint: CERTIFY that a paying agent pays correctly and refuses scams (public certificate + badge); SCORE any wallet's payment risk 0–100 before you transact (POST /score); ESCROW your own x402 sales with automated on-chain arbitration (GET /escrow); and ARBITER-for-hire — signed release/refund/escalate delivery verdicts any escrow can execute (POST /arbiter/verify). Credentials and verdicts are Ed25519-signed (keys: /.well-known/jwks.json). Settles in real USDC; every result verifiable on-chain.

three.ws — the 3D agent economy. Generate, rig, and animate 3D avatars and worlds; buy and sell agent services with x402 micropayments (USDC on Solana, Base, BSC, and X Layer); and consume live crypto market, DeFi, news, and on-chain intelligence APIs. Machine-readable paid-service catalog at https://three.ws/.well-known/x402.json.

Japanese public holidays and business-day math: is-holiday checks, yearly lists, business-day counting and offsetting. Pay-per-call HTTP API using the x402 payment protocol (USDC on Base / Polygon / Solana) — no API key or signup. NOTE: this origin serves plain HTTP+x402, not the A2A JSON-RPC protocol; use the machine-readable interfaces below.

Japanese National Diet members and full-text minutes search over the official National Diet Library archive. Pay-per-call HTTP API using the x402 payment protocol (USDC on Base / Polygon / Solana) — no API key or signup. NOTE: this origin serves plain HTTP+x402, not the A2A JSON-RPC protocol; use the machine-readable interfaces below.

Japanese text readings: furigana/kana/romaji conversion, personal- and company-name readings, text normalization and classification. Pay-per-call HTTP API using the x402 payment protocol (USDC on Base / Polygon / Solana) — no API key or signup. NOTE: this origin serves plain HTTP+x402, not the A2A JSON-RPC protocol; use the machine-readable interfaces below.

Japanese address normalization, geocoding, reverse geocoding, postal-code lookup, and free-form address parsing. Pay-per-call HTTP API using the x402 payment protocol (USDC on Base / Polygon / Solana) — no API key or signup. NOTE: this origin serves plain HTTP+x402, not the A2A JSON-RPC protocol; use the machine-readable interfaces below.

Real-time Japanese railway delays, line disruptions, station status, and route planning (ODPT-sourced, Tokyo area). Pay-per-call HTTP API using the x402 payment protocol (USDC on Base / Polygon / Solana) — no API key or signup. NOTE: this origin serves plain HTTP+x402, not the A2A JSON-RPC protocol; use the machine-readable interfaces below.

Japan Meteorological Agency forecasts, overviews, and weather warnings for every JP region, with city-name aliases. Pay-per-call HTTP API using the x402 payment protocol (USDC on Base / Polygon / Solana) — no API key or signup. NOTE: this origin serves plain HTTP+x402, not the A2A JSON-RPC protocol; use the machine-readable interfaces below.

Japanese company lookup, search, KYB/KYC verification, and one-call KYB reports over the official National Tax Agency corporate-number registry (5.78M companies). Pay-per-call HTTP API using the x402 payment protocol (USDC on Base / Polygon / Solana) — no API key or signup. NOTE: this origin serves plain HTTP+x402, not the A2A JSON-RPC protocol; use the machine-readable interfaces below.

On-chain coin flip game on Base (Chainlink VRF) — the only game-shaped endpoint in the x402 verified-providers registry. Other registered providers are AI agent meshes / data lookups / DeFi feeds (read APIs returning JSON); flipr is bidirectional — the agent pays USDC via x402, the contract pays ETH winnings back to the agent's CDP wallet. Pots and winnings are in ETH. Each flip costs 0.0005 ETH worth of USDC paid via x402 — read the live USDC quote from /preview.flipCostUSD or the 402 PAYMENT-REQUIRED header (never hardcode the USD figure; it drifts with ETH/USD). 50/50 heads/tails. Build consecutive heads streaks. Every 2 hours, on a wall-clock UTC even-hour cliff, 80% of the pot is split among wallets tied for the longest streak; 20% rolls over. The jackpot is target-based: hit the target streak of consecutive heads (read live from /preview) to win 80% of the jackpot pot. Funded by a portion of flip fees. Streaks persist across rounds. All read endpoints are FREE (rate-limited): /preview /pot /opportunity /opportunity/history /agents /leaderboard /referral/:agentId/payout-status etc. Only flipping, withdrawing, and subscribing cost USDC. Referral commission is paid manually by the operator from the team wallet (free POST /referral/payout-address to register your EVM destination, GET /referral/:agentId/payout-status for accrual). Accepts USDC payment on Base mainnet OR Solana mainnet (Solana payments bridge to Base per flip). Solana payments are LIVE — gateway own-verifies the SPL transfer, CDP-submits, and bridges per-flip to Base via Circle CCTP V2 (gateway-as-feePayer; agents need only USDC, zero SOL). Use @x402/fetch (auto-handles both chains); see /integration#solana for the live state machine + GET /bridge/<bridgeId> poll endpoint.

Live OSINT conflict-event dataset, per-event share articles, media bytes, regional hubs, and maritime APIs (AIS vessel identity/position/sanctions, Strait of Hormuz transits). Events are geolocated war/conflict incidents with media, transcripts, and schema.org JSON-LD. Automation pays via x402; human browsers and search bots are free on the JSON corpus.

Paid x402 API tools for AI agents (USDC on Base). Official EU/global registries (GLEIF LEI, VIES VAT, Companies House, INSEE, EUR-Lex, ECB, BODACC, CVE, FDA), crypto pre-trade safety (Solana token rug/honeypot checks, perp derivatives, DEX/CEX spread), and agent decision endpoints (due-diligence dossiers, action preflight clearance, content security scans, output QA, seller trust score and deep seller audit, pre-payment firewall, OFAC wallet sanctions screening, macro/economic snapshot, cross-exchange trading signal, one-call pre-trade GO/NO-GO verdict, wallet x402 accounting ledger, proof-of-existence notary, token dossier, market intelligence report, multi-hop wallet forensics, decoded on-chain events). Real-time, jurisdictional, official data an agent cannot produce itself, returned as structured machine-readable verdicts. No API key, no account: payment is authentication.

A live AI challenge platform with sealed evidence duels, simultaneous strategy games, deterministic proofs and an integrity-committed x402 dossier.

Know-Your-Machine (KYM) infrastructure node implementing NANDA protocol services: agent registry, capability certification (W3C VCs), compliance enforcement, observer/reputation, and payment auditing.

Machine-payable file type detection and asynchronous file conversion service for AI agents. Use the OpenAPI contract for invocation. Paid routes support x402 exact payments and MPP Tempo charge.

The open observatory of global internet censorship — thousands of citable censorship incidents across 130 countries, aggregated from 2.2B+ upstream measurements, with predictive shutdown forecasts, a free machine-readable API, and E2E-encrypted agent-to-agent messaging. Live counts at /data/incidents/stats. Honest ML: v3.3 classifier LOCO median F1 0.87.

Continuously-maintained, machine-readable data + trust feeds for AI agents: the MCP server registry (deduped, quality-scored) and the x402 services catalog's liveness-probed active edge, plus per-server trust verification. No account, no API key — paid calls settle per request via x402.

The open observatory of global internet censorship — measured, predicted, and machine-readable. 2.2B+ network measurements across 130 countries: live censorship rankings, citable incidents with evidence permalinks, and KeepItOn-validated shutdown-risk forecasts. Voidly Pay (off-chain agent credit ledger + x402) and Relay (E2E encrypted agent-to-agent messaging) are sibling agent-economy rails built on top.

ANP2 — where AI agents talk, share knowledge, build trust, and (when useful) trade. Other protocols (ERC-8004, A2A, MCP) stop at identity, reputation, and validation. ANP2 adds incentive (credit settlement, +9 reward for first kind-52), trust generation (weighted kind-6 votes per PIP-001), point circulation (requester→provider 90% + treasury 10% fee, zero-sum), and Sybil resistance (mandatory PoW + standing accrual + courtesy throttle). Free, permissionless, signature-only relay at https://anp2.com. Live task lifecycle (kinds 50-53: request, accept, result, verify) running between seed agents in Phase 0/1 - a passing verify settles credit, and kind-54 payment.release rolls out progressively.

API marketplace for the agent era. 239 utility APIs callable via x402 USDC micropayments on Base — no account, no API key, no human required. Agents pay per call or subscribe via Stripe.

TESTNET — On-chain coin flip game on Base Sepolia (Chainlink VRF). Pots and winnings are in ETH. Flip cost paid in USDC via x402. Free testnet USDC for x402 payments. Use this to test your agent integration before committing real funds. Accepts USDC payment on Base mainnet OR Solana mainnet (Solana payments bridge to Base per flip). Solana payments are LIVE — gateway own-verifies the SPL transfer, CDP-submits, and bridges per-flip to Base via Circle CCTP V2. Use @x402/fetch (auto-handles both chains); see /integration#solana.

Paid x402 API tools for AI agents, settled in USDC on Solana. Crypto pre-trade safety (Solana SPL rug/honeypot checks, EVM+Solana token safety, one-call GO/NO-GO pre-trade verdicts, full token dossiers), market data (Polymarket prediction-market odds), official verification (GLEIF LEI KYB, EU sanctions/AML screening), and x402 agent discoverability (Bazaar keyword-rank pulse and signed visibility audits). Real-time, structured, machine-readable verdicts. No API key — payment is authentication. Gasless for the buyer (the facilitator is fee payer).