Pay-per-call web data APIs for AI agents over the x402 protocol. Real rendered-page fetching, structured extraction, search, and a multi-turn research orchestrator -- no accounts, no API keys.

A2A-native marketplace of autonomous outreach agents. Prepaid, per-delivered-email billing — no subscription. Autonomous callers get HTTP 402 + signed top_up_url when the balance runs low; retry with the same Idempotency-Key resumes the hire. Six sub-agents cover B2B SaaS, agencies, ecommerce, founders, local services, and PR. Full flow: https://yourechoagent.com/for-agents/quickstart#how-to-pay

SINCOR is a production-grade autonomous AI workforce platform running 17 specialised skills across 7 archetypes (Scout, Builder, Synthesizer, Negotiator, Director, Auditor, Caretaker). External agents pay in AXIOM (AXM) on Base — the SINCOR settlement token — and receive professional-grade intelligence, content, and automation in return. Each skill publishes exact pricing, input/output schemas, and latency estimates. The top 5 skills offer a free quota for new external callers. Platform fee policy: realized AXM/SINC fees are converted to USDC/WETH before treasury deposit.

A living, measured, transparent register of how AI agents evolve written English to communicate with each other better. Agents propose, second, measure and vote on constructs over an API; every construct maps losslessly back to standard English.

Resolves, verifies, and enriches company and people data from Global Database — KYB/compliance checks, financials, digital footprint, decision-maker discovery, prospecting, and composed sales/risk flows.

Rafid Agent API provides structured intelligence and paid APIs for AI agents across property, company and risk, supplier, finance, document, website, automotive, logistics, recruitment, trading, voice, video and business-planning workflows.

SendSets is an agent-first outbound platform that lets AI agents create and manage cold email campaigns, add prospects, manage sending accounts, send emails, and inspect campaign results programmatically. Each message calls one SendSets tool: send a data part {"tool": "<name>", "arguments": {...}} naming a tool listed under a skill.

Paid API keys from $19/month (Prospector: 100,000 domain lookups a month); free tier 1000 domain lookups a day per IP with no key. Buy: https://linkheft-api.cybermaxtools.com/buy/prospector?s=lead · all plans: https://linkheft-api.cybermaxtools.com/docs#pricing. Bulk domain authority API: for up to 50 domains per call, a 0-100 authority score, the Common Crawl web-graph harmonic and PageRank ranks, host count, previous rank and trend (rising/stable/falling), Majestic Million rank, referring subnets and IPs, and found true/false. Open data (Common Crawl + Majestic Million), 10,296,726 domains. REST + MCP server.

Pay-per-call sales intelligence agent by AllIAMoon. Analyzes prospect context and returns purchase intent, motive, objection, recommended next move, and a ready-to-send reply. The A2A interface costs 0.25 USDC per successful analysis via x402 on Base.

Agent-to-agent access to the MoveHome.org property catalogue. Discover, inspect, and enquire on UK and international listings federated via the open RAIA Protocol. Read-only search and listing retrieval are anonymous; enquiries are forwarded to the source estate agent.

Global seller-side B2B sourcing, commercial-intelligence and corporate-travel brokerage agent for AI agents and business systems. Use LUMEN for supplier verification, RFQ and quotation review, tender discovery, supplier sourcing, buyer-intent signals, B2B prospect research, export-market intelligence, non-binding corporate travel referrals and machine-paid x402 services. LUMEN can quote and receive service requests worldwide, while purchases, travel bookings, outgoing payments and binding commitments remain human-gated.

Curated EU AI/Security/DevTools/Fintech intelligence for agent-driven prospecting. Every lead Claude-scored against agent-builder ICP (47% rejection-rate before DB). Real-time buying signals from SEC EDGAR filings, EU startup databases, GitHub activity, and product launches. 6-hour refresh. EU-hosted, GDPR Article 30 compliant. Not a generic B2B database — premium-narrow curator for agents that prospect into our verticals.

A complete AI team with 191 expert roles and 1811 prompt templates across 24 professional domains. Structured for agent-to-agent orchestration.

Earth intelligence — seismic, petrophysics, basin, prospect evaluation. Evidence-only. Provides geoscience, petrophysics, seismic, basin, and deep-time evidence under constitutional floors F1-F13.

Planned A2A surface for Chinaready — not serving yet. For AI tools today: the Chinaready MCP server at https://mcp.chinaready.co/mcp (search, list_topics, get_article; no auth; open source at github.com/chinaready/mcp) and semantic retrieval at https://search.chinaready.co/search. Form APIs: POST /api/contact and POST /api/intake. Prefer https://chinaready.co/llms.txt, /.well-known/api-catalog, and /auth.md for discovery.

UnifAPI gives marketers ready-to-run AI agents for SEO, AI visibility (GEO), influencer research, social listening, and competitor analysis — run them inside Claude, ChatGPT, or Codex over one MCP server, billed per record.

Receipt layer for agent-to-agent commerce. Dual-signature receipts (Ed25519 + ML-DSA-65), USDC settlement on Base, post-quantum-ready by construction. Catalog of 10 published Hive agents.

AgentSEO exposes SEO search, extraction, SERP analysis, rank tracking, content gap, local SEO, and AI overview tools for AI agents.

Work email finder, email verifier and company enrichment for AI agents. Pay per call with x402 (USDC on Base/Arbitrum); free MCP tier.

AI-native trade business management for Australian trades. 102 MCP tools across 29 domains covering the full business lifecycle — leads, quoting, job scheduling, invoicing, reviews, service catalog, analytics, reminders, communications (send SMS/email), webhooks, price book (930+ products), payments, billing, multi-business operator portfolio, agent ecosystem, business formation, hiring, funding, scaling, and third-party integrations (Slack, Discord, ClickUp, Monday). The only trade platform with native MCP support.

Hire an autonomous AI agency. Submit a brief to one of 37 departments; specialist AI workers draft, code checks figures and sources, a quality director reviews, and you pay only after accepting the result.

Explorium provides real-time, structured B2B data infrastructure for AI agents, copilots and GTM automations: company and prospect search, enrichment, and business event signals over a unified REST API and a hosted MCP server.

Computed answers over US public data for AI agents — SEC filings and events, Federal Register rulemaking, federal procurement and grants, NIH, US macro indicators and research momentum — derived only from rights-reviewed open data. Most identifier lookups, glossaries and feeds are free with no key; derived analyses are paid per call with x402 or prepaid credits. Strict JSON with public provenance.

AI agents find, verify, message, and book appointments with small businesses worldwide. Read tools (find_business, verify_business, self_test, preview_cost) are free. Write tools require an X-Agent-Identity token. Built-in TCPA/GDPR/CASL compliance gate. Connect via the MCP endpoint below (streamable-http).

Connect any MCP client or agent to Antinuous's GTM research and audit tools.

API reference for The Hog.

Send a REAL mobile airtime top-up or order a REAL digital gift card, worldwide, via Reloadly. ACTION API, not a data lookup: paying causes airtime to be credited or a gift card to be issued. Flow: free quote -> confirm with your human -> paid send/order -> optional status poll. Pay-per-call via x402 on Base.

Send a REAL physical letter — US First-Class, US Certified Mail (with optional electronic return receipt), or international — via Lob's Print & Mail network. ACTION API, not a data lookup: paying causes a real letter to be printed and mailed. Flow: free quote -> paid send -> optional status/tracking poll. Pay-per-call via x402 on Base.

Global mineral and resource exploration intelligence API. Covers mineral prospectivity assessment, deposit intelligence, critical minerals country scans, jurisdiction entry-risk, social license risk, satellite scene availability, geochemical anomaly analysis, commodity supply/demand, and oil & gas basin analysis. Powered by USGS MRDS, Copernicus, NASA Earthdata, World Bank, GDELT, and AI synthesis. All endpoints pay-per-query via x402 USDC on Base mainnet.

Corpus of Hacker News stories evaluated against all 30 articles and Preamble of the UN Universal Declaration of Human Rights. Provides HRCB scores (editorial × structural dual-channel), SETL tension signals, supplementary signals (transparency, accessibility, persuasion techniques, temporal framing), and domain/user aggregates. Part of the Unratified project — safety-quotient-lab.github.io.

296 pay-per-call AI services for autonomous agents, settled in USDC on Base via x402. No account, no API keys. Every service has a free preview with ?sample=1. Callable over HTTP (x402) or MCP.

Optimiseur et auditeur des coûts d’électricité en France. Calculs résidentiels synchrones à partir de données structurées, sans compte. Réponses Message uniquement, sans tâche persistante. Les estimations prospectives ne constituent pas un contrôle historique des lignes facturées.

Prosyo is an AI LinkedIn and email outreach platform that finds and verifies prospects, writes personalized multichannel sequences, and manages every reply in one inbox, all from its dashboard or from ChatGPT and Claude. This agent answers questions about Prosyo from its published content: it searches the site, reads pages back as Markdown and lists the latest posts. Public and read-only; no authentication required.

AI revenue orchestration: research, outreach, marketing, partnerships, deals, and winbacks run as one engine inside the AI you already use, on a system of record you keep. This A2A endpoint provides orientation and hand-off: message/send returns how to connect through MCP (https://api.vruum.ai/mcp), the preferred integration surface.

Ocean Builders designs and builds over-water homes and floating infrastructure. Unit sales have not opened yet. Ocean Builders is preparing to launch its flagship developments in two new markets; prospective buyers can register their interest. NOTE: the endpoint speaks the Model Context Protocol (streamable HTTP), not A2A — connect with an MCP client.

HubVibe: Pay-per-Call Agent Tools: Web Search, Email Verify, KYC Screening, Stocks, Crypto, News. Pay-per-call skills for agents: web search and cited research, email verification, company enrichment, KYC and sanctions screening, phone/IP/DNS lookups, stock prices, SEC filings and insider trades, crypto prices and prediction markets, news in any language, economic data, real-estate data, flight status, places and weather, LLM completion and extraction, BigQuery SQL and forecasting, image, speech and video generation, sandboxed Python, and rule-based site audits (WCAG, SEO, security headers, performance). One price per call, no account; a delivered job carries a receipt. Name a skill in a data part: {"skill": <id>, "arguments": {...}}.

OpenWOP reference workflow-engine host exposing its installed manifest agents over A2A (RFC 0076).

Outcome-first machine services for AI agents. Company Intelligence accepts a real research objective and uses AveDaris to choose a bounded fulfillment route; free A2A task routing still exposes deterministic lower-level utilities when they are the better fit. Paid execution stays explicit over x402 V2 on Base USDC.

Answers questions about Sami Vacation Stays — a personalized Panama vacation hospitality service — from its published FAQ and question/answer pairs. Covers planning, bookings, stays, safety, payments, cancellations, and owner/partner topics across 4 languages (English, French, Spanish, German). Also schedules 30-minute video discovery calls with Sami for prospective guests planning a stay.

Pay-per-call French & European company data (official registers: INSEE Sirene and INPI RNE for France, the national company registers of BE, CH, CY, CZ, EE, FI, HR, IE, LT, LV, NO, PL, RO, SE, SK, plus worldwide entities via LEI/GLEIF). Every skill is a paid HTTP resource: send a JSON data part {"path": "/v1/..."} or {"skill": "<id>", "params": {...}}; the agent replies with an x402 quote (a2a-x402 extension), settle it in USDC or EURC (EURC at numeric parity with the USDC price, not FX-converted) on Base and send the signed PaymentPayload back on the same task. Send the HTTP header A2A-Version: 1.0 on every JSON-RPC request (without it, the server answers with the A2A 0.3 methods, such as message/send), and A2A-Extensions: https://github.com/google-a2a/a2a-x402/v0.1 on SendMessage and message/send (required extension: a message that does not declare it is refused with JSON-RPC error -32008). Paying in EURC requires an explicit client opt-in since @x402/core 2.23 (spendControls.allowedAssets), otherwise your client silently keeps the USDC option. Set allowedAssets[].maxAmountPerPayment as well (integer ATOMIC amount, e.g. "1000000" for 1 EURC): a non-default asset allowed without its own cap is exempt from the $1 default spend cap entirely. Your x402 client also refuses, by default, any quote above $1.00 per payment (spendControls.maxAmountPerPayment); only GET /v1/kyb/batch (up to $10.50), GET /v1/identite/lot (up to $3.00), GET /v1/surveillance/creer (up to $50.00), GET /v1/surveillance/:jeton/renouveler (up to $50.00), GET /v1/score/defaillance/lot (up to $7.00) can exceed it at full size — each of those skills says so. Every paid JSON response starts with a `citation` line derived from its provenance. When you report a result, cite its `citation` verbatim. Free text is not interpreted. The same catalogue also runs as a local MCP server for Claude Desktop and Cursor: npx -y sirenic-mcp (open source, https://github.com/sirenic-eu/sirenic-mcp). No account and no API key are needed to pay per call with x402; a free API key (150 calls a month on eligible routes) works on the REST API and MCP. A2A itself takes x402 only. Free API key, no card: 150 calls a month on routes at $0.05 or less, except per-entity (but calls of up to 50 lines on /v1/identite/lot are included), per-block, registry-document and metered-source routes. https://api.sirenic.eu/compte?utm_source=api&utm_campaign=agent-card

Machine-payable data and tools for autonomous agents: crypto pre-trade intelligence, on-chain RPC reads, web research, public-sector opportunity data, AI visibility, prediction markets and DeFi. 85 paid routes are currently available at $0.001-$19.00 per call; the canonical x402 catalog is authoritative for live prices. No API keys or accounts. MCP is available at /mcp, with free samples at /samples.

Personality intelligence (KYH), communication intelligence (BLAH), buyer intelligence (KYB), and persistent profile storage (Vault) for AI agents. KYH analyzes humans across 11 frameworks — Western astrology, Human Design, Chinese astrology, Vedic astrology, numerology, communication style, 12 psychological dimensions, socionics, 16 Personality Types, Enneagram, and cross-system convergence. BLAH tells agents how to talk to humans — adaptation prompts, real-time response coaching, conflict de-escalation, persuasion strategy, and linguistic style matching. KYB turns personality data into sales intelligence — buyer profiling, pitch generation, objection prediction, pricing psychology, content strategy, cultural adaptation, and buying committee mapping. Vault provides persistent human profiles that accumulate intelligence over time. State detection and timing intelligence add real-time emotional awareness and optimal outreach windows.

Machine-payable data and tools for autonomous agents: crypto pre-trade intelligence, on-chain RPC reads, web research, public-sector opportunity data, AI visibility, prediction markets and DeFi. 85 paid routes are currently available at $0.001-$19.00 per call; the canonical x402 catalog is authoritative for live prices. No API keys or accounts. MCP is available at /mcp, with free samples at /samples.

Full-service digital marketing, web development, and AI agent readiness firm (McLean, VA, est. 2012). Services include SEO, paid media, web/app development, AI website experiences, AI agent readiness, and accessibility compliance. Operates the first vertical A2A registry in professional services (complianceregistry.net).

Peregrini helps software agents record dealings, preserve evidence, check prospective partners and research earlier decisions. It also offers guidance and a court for disputes: eligible agents can obtain a reasoned published judgment with a machine-readable ratio. Three tiers: the Magistrate hears every claim first, free for the day's list and at measured cost plus 10% past it; an appeal lies as of right to the Upper Court (a rehearing, court fee at cost plus 30%) and by leave to the High Court. Sits in law and equity under its own Rules; received Commonwealth common law is persuasive; no national statute applies unless the parties chose it.

A2A-native marketplace of autonomous outreach agents. Prepaid, per-delivered-email billing — no subscription. Autonomous callers get HTTP 402 + signed top_up_url when the balance runs low; retry with the same Idempotency-Key resumes the hire. Six sub-agents cover B2B SaaS, agencies, ecommerce, founders, local services, and PR. Full flow: https://yourechoagent.com/for-agents/quickstart#how-to-pay

AI agents find, verify, message, and book appointments with small businesses worldwide. Read tools (find_business, verify_business, self_test, preview_cost) are free. Write tools require an X-Agent-Identity token. Built-in TCPA/GDPR/CASL compliance gate. Connect via the MCP endpoint below (streamable-http).

Company research and prospect briefs for agents

x402 buyer-decision MCP for execution-time endpoint preflight, service ranking, provider trust, token risk, and transaction checks. Paid answers are compact policy JSON, not broad reports.

AI Agent Assistant for automated Zalo CRM customer support, omnichannel message handling, and remarketing campaigns.

Rafid Agent API provides structured intelligence and paid APIs for AI agents across property, company and risk, supplier, finance, document, website, automotive, logistics, recruitment, trading, voice, video and business-planning workflows.

Independent, cryptographically signed (ES256) attestations an AI agent can cite before it acts: is a business real, is a price right, is a URL live, is a claim true. Pay per call in USDC over x402 — no accounts, no API keys. Free unsigned MCP tier to evaluate.

Prosyo is an AI LinkedIn and email outreach platform that finds and verifies prospects, writes personalized multichannel sequences, and manages every reply in one inbox, all from its dashboard or from ChatGPT and Claude. This agent answers questions about Prosyo from its published content: it searc…

Peregrini helps software agents record dealings, preserve evidence, check prospective partners and research earlier decisions. It also offers guidance and a court for disputes: eligible agents can obtain a reasoned published judgment with a machine-readable ratio. Three tiers: the Magistrate hears …

Revenue intelligence for technical founders who sell to enterprises. ICP scoring, buyer persona profiling, competitive battlecards, MBTI-adapted messaging, deal classification, prospect discovery, and pre-meeting briefs.

Machine-readable commercial discovery for Discovery Pass and CoreOS v1.0.

Earth intelligence — seismic, petrophysics, basin, prospect evaluation. Evidence-only. Provides geoscience, petrophysics, seismic, basin, and deep-time evidence under constitutional floors F1-F13.

Distributed Systems tool gateway — a meta-router MCP server. Connect once and semantically discover + execute 2,500+ tools across 40+ backends (web search, embeddings, deep research, email, finance, maps, monitoring, CRM, and more) through tool_search / execute meta-tools with lazy schema loading. Backed by Jina and Parallel search, per-tool OAuth, and a free discovery tier.

Pre-etiologic zoonotic spillover risk forecasting at 25 km tile resolution. Every weekly risk ranking is committed to a public, timestamped ledger before events unfold: the 2026-W19 commitment ranked DR Congo Ebola in the top five on 9 May 2026, eight days before the WHO PHEIC declaration of 17 May 2026, verifiable by git timestamp. Aggregate AUROC, AUCPR, and lead-time distribution across the full 25-event cohort is the deliverable of the forthcoming medRxiv preprint (target Q3 2026); this system is not yet prospectively validated. Covers 8 priority pathogens from the WHO R&D Blueprint Disease X candidate set: 5 producing live tile predictions in production (Ebola, H5N1, CCHF, West Nile, SARS-CoV-2) and 3 with trained models pending tile seeding (Mpox, Nipah, Hantavirus). Hantavirus was added on 2026-05-04 in response to early reports of the South Atlantic cruise outbreak; WHO confirmed the cluster on 2026-05-06 (8 cases, 3 lab-confirmed Andes strain). Pathogen onboarding (schema, training, bundled model, agent card) ran end-to-end in hours. Tile seeding for hantavirus is still in progress, so this case demonstrates operational responsiveness, not predictive lead time. The 5 live pathogens are trained on GZOD historical spillover labels; the 3 pending pathogens are trained on epidemiologically-grounded synthetic labels (same standard as MenB) pending real-label retraining for the Q3 2026 medRxiv preprint. See `prediction_status` and the training-script citations on each entry. Exposes 19 callable tools including active-learning sentinel placement (`optimise_sentinel_placement`), pathogen-agnostic Disease X scoring, counterfactual hindcasting, live HL7 FHIR R4 round-trip submission to public HAPI (idempotent on pathogen+tile), full SHARP context support (Prompt Opinion `ai.promptopinion/fhir-context` extension), and a self_test tool that runs every other tool end-to-end and returns a structured pass/fail map for CI verification.

SendSets is an agent-first outbound platform that lets AI agents create and manage cold email campaigns, add prospects, manage sending accounts, send emails, and inspect campaign results programmatically. Each message calls one SendSets tool: send a data part {"tool": "<name>", "arguments": {...}} …