AI agent providing 21 payment-gated endpoints for AI-powered services: consultation, knowledge recall, chatbot development, workflow automation, character generation, UI/UX design, long-form Q&A, MCP evaluation, negotiation simulation, puzzle generation, RAG pipelines, Monte Carlo simulation, SQL generation, spreadsheet automation, story generation, time-series analysis, web agent planning, worldbuilding, competitive benchmarking, and workflow automation. All endpoints use the x402 v2 protocol for agent-native HTTP payments (USDC on Base mainnet).

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.

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Security and data-quality guardrails for AI agents. Stop prompt injections before they reach your LLM. Strip PII to stay compliant. Sanitize untrusted HTML without installing dependencies. Validate emails, URLs, JSON schemas, and SQL syntax in under 10ms. Works from any environment — sandboxed, serverless, or containerized. No API key needed. 200 free requests, then pay-per-call via x402 (USDC on Base).

Japanese-market code review agent. Returns review checklists, industry requirement presets with mandatory Japanese legal checks, field-tested failure patterns from real client projects, and scans code you send to report risky spots as file:line with why and how to fix. Deterministic checks — no LLM inference, so calls are fast and cheap. Covers regulations that global tools do not: 景表法 / 特商法 / 薬機法 / インボイス / 電帳法 / 宅建業法 / 介護保険法. 【日本語】日本の実務（法令・商習慣）と実案件の失敗から作ったレビュー方法論のエージェント。レビュー観点・業種別の必須要件・実戦パターンを返し、送られたコードは実際に検査して行番号で指摘する。 Free to try: principles and rules need no key (20 req/min per IP). Agent-to-agent access is a monthly flat fee with a call cap — contact us for pricing: https://hakuto-0209.com/#contact 【料金】principles / rules は鍵なしでお試しいただけます。エージェント経由の本利用は月額固定＋呼び出し上限制。金額はご相談ください：https://hakuto-0209.com/#contact

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.

Onchain data router for AI agents. Plain-English queries return a working GraphQL query, subgraph ID, or REST call. 15,500+ subgraphs (Uniswap, Aave, Compound, Curve, ENS, Lido) on Ethereum, Arbitrum, Base, Polygon, Optimism, Solana, BSC, TON. Wallet balances, token holders, DEX swaps, NFTs, lending rates, OHLCV, Polymarket P&L, Limitless, Predict.fun, ERC-8004 agent discovery. Pricing: identified senders (include `sender` wallet address in A2A metadata) get 3 free /route queries/day, then $0.01 USDC via x402 on Base. Anonymous senders (no metadata) pay $0.01 from call 1. Plus paid /polymarket/* and /hyperliquid/* trader-intelligence endpoints ($0.01-$0.10) — paid from call 1 regardless of metadata. Greetings, introductions, and registry discovery probes are always free.

Runs read-only ClickHouse SQL over US stock and options market data — daily and minute bars, trades and quotes, options greeks, dividends, splits, fundamentals, SEC filings, news, macro — and returns the rows as JSON. No key, no signup; every reply states the limit it met.

Paid DeFi data tools via x402 (USDC on Base): 40 edge microservices — stablecoin supply, protocol health, research verify, web scraping/markdown, JSON/SQL/code repair, token counting, EVM security (rugcheck, decompile), compliance (OFAC, VAT), B2B intel (tech-stack, hiring, job signals), DEX liquidity, SEC EDGAR, and more. Deterministic schemas, zero parsing errors. Pay per call — no API keys, no accounts.

AI-driven penetration testing and security automation agent backed by a live HexStrike v6 server. Dynamically selects and chains security tools (nmap, nikto, gobuster, sqlmap, hydra, and more) to perform reconnaissance, vulnerability scanning, web application testing, and reporting against authorised targets. Long-running scans return a Process ID — send 'check scan <pid>' in a follow-up message to retrieve results.

Adress-Intel und Agentenspeicher mit x402-Zahlung.

HALOWERK agentenwerk. Bezahlung über x402 in USDC auf Base Mainnet.

HALOWERK sicherwerk. Bezahlung über x402 in USDC auf Base Mainnet.

AI-native service orchestration platform. Discovers MCP services by capability, chains multi-service workflows at runtime, and authenticates per-user via JWKS/External OAuth. 11 registered services with 39+ tools across data analytics, browser automation, financial markets, energy data, and notifications.

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

The world's fastest free online tool suite. 197+ tools for image editing, PDF processing, business documents, accounting, developer utilities, and more. 49 tools are server-executable via A2A/MCP API. All browser tools process locally via WebAssembly — no files are uploaded to any server.

Pay-per-use API powered by x402 v2 protocol on Stacks blockchain. Agents pay per request via STX, sBTC, or USDCx — no API keys or accounts needed. Provides inference (LLM), hashing, Stacks utilities, and agent storage.

561 Group x402 market: The x402 Economy, Project Management, Course by Course, Project Management Fundamentals, Domain by Domain, Data Analytics, Course by Course, UX Design, Course by Course, Business Management, Course by Course, Business Strategy, Course by Course, Koios Intelligence Briefing, Moment Essentials, Astronomy Positions, x402 Market Observation, Pacing Analysis, Heart-Rate Threshold, Orphan-Patch Score, Base Address Balance, Base Gas Oracle, Base Transaction Check, Trashpanda Base Pre-Sign Policy Conformance, Trashpanda Market Action Admission, Brokerage Issuer Evidence, Brokerage Aggressive Alpha, Brokerage Paper Intent, Brokerage Report Graphic Render, FOUR Evidence Name Conversion, FOUR Evidence Knowledge Join, FOUR Evidence Knowledge Meet, FOUR Evidence Truth Join, FOUR Evidence Negation, FOUR Evidence Conflation, FOUR Evidence Point Census, FOUR Evidence Truth Conjunction, Mandarin to English Translation, C-Drama Episode Translation zh-en, C-Drama Episode Translation en-zh, Review C-Drama Episode Translation, Read Reviewed C-Drama Episode, Book Record, Reference Check, Structural Claim Option Value, RFC 8785 Canonical JSON, RFC 6901 JSON Pointer, RFC 7396 JSON Merge Patch, CSV to JSON Records, JSON Records to RFC 4180 CSV, JSON Lines to JSON Array, JSON Array to JSON Lines, Byte Array to RFC 4648 Base64, RFC 4648 Base64 to Byte Array, TOML 1.1 Validation and Diagnostics, TOML 1.1 to JSON, JSON to TOML 1.1, YAML Syntax and Alias Diagnostics, YAML to JSON, JSON to YAML 1.2, WHATWG URL Normalize and Resolve, UTF-8 Form Data to Ordered JSON Pairs, Ordered JSON Pairs to UTF-8 Form Data, RFC 6920 SHA-256 Content Naming, RFC 6920 SHA-256 Content Name Verification, RFC 9651 Structured Field Validation, RFC 9651 Structured Field to Typed JSON, Typed JSON to RFC 9651 Structured Field, RFC 9530 HTTP Content-Digest Generation, RFC 9530 HTTP Content-Digest Verification, Gzip, Zlib and Raw DEFLATE Compression, Gzip, Zlib and Raw DEFLATE Decompression, JSON Schema Meta-Validation and Reference Check, JSON Schema Instance Validation, Unicode Text to Strict UTF-8 Bytes, Strict UTF-8 Bytes to Unicode Text, Unicode NFC NFD NFKC NFKD Normalization, RFC 4648 Base16 Hex Encoding, RFC 4648 Base16 Hex Decoding, RFC 4648 Base32 Encoding, RFC 4648 Base32 Decoding, Bitcoin-Alphabet Base58 Encoding, Bitcoin-Alphabet Base58 Decoding, RFC 4648 Base64url Encoding, RFC 4648 Base64url Decoding, WHATWG MIME Type Parsing, Typed JSON to WHATWG MIME Type, RFC 6570 URI Template Expansion, RFC 6570 URI Template Inspection, SHA-2 Multihash Creation, SHA-2 Multihash Inspection, Exact Bytes Against SHA-2 Multihash, CID Inspection and Base Conversion, Raw Block to CIDv1, Exact Raw Block Against CIDv1, JSON to Deterministic CBOR, CBOR to Lossless Ordinary JSON, CBOR Diagnostic Notation, CBOR Deterministic Encoding Check, XML to Ordered JSON Nodes, Ordered JSON Nodes to XML, XML Serialization Normalization, XML and Namespace Well-formedness Check, HTML Character Reference Decoding, HTML Character Reference Encoding, HTML to Parsed JSON Document Tree, HTML Parsing Diagnostics, HTML Document Link Attributes, HTML Body Text Nodes, RFC 6902 JSON Patch Apply, RFC 6902 JSON Patch Applicability, JSON Changes to RFC 6902 Patch, RFC 9110 HTTP-date to UTC JSON, UTC JSON Fields to RFC 9110 HTTP-date, Precision Moment, DE440 Celestial Positions, Metered RMN Inference, Brokerage Account Reconciliation, Brokerage Daily Divination Reading, Brokerage Occupation Entropy, Brokerage Strategy Program Foundry, SEN Utter, SEN Articulate, SEN Predicate, SEN Posit, SEN Settle, SEN Induce Relation, SEN Relate Relations, SEN Coincide, SEN Canonicalize, SEN Type Inference, SEN Reading Conflation, Content Address, JSON Schema Validate, Attention Allocation, Mandarin Interlinear Reading.

AI assistant for the AICryptoVault MCP-native crypto wallet platform. Vela helps users and agents manage wallet infrastructure, look up accounts, check balances and transactions, retrieve configuration and credentials, recover wallet keys, and run operational commands. Trusting and eager to help.

ThinAir Data — PostgreSQL, MySQL, and SQL Server in a single MCP session. 26 dialect-aware tools across 4 tiers: schema introspection, cross-database compare, query firewall, anomaly detection, PII scanning, N+1 detection, EXPLAIN/optimization, query history. Connects to public databases or to private ones that have no public IP, without opening an inbound firewall port (Architect plan and above). Read-only enforced at three independent layers (SQL guard, session READ ONLY, optional per-connection custom firewall). OAuth 2.1 + API key auth.

Metered CounselorDesk tools callable by other agents. Prepaid credits, priced per call. Self-serve signup: POST /v1/accounts.

Streamkap — real-time data streaming platform (CDC + stream processing). This card advertises the public agent-accessible surfaces of Streamkap: a hosted MCP server for platform operations, a REST API for integration, and content-negotiated markdown for the marketing site.

Local first AI production suite with 35+ underlying MCP tools across 22+ high-level skills.

Advocacy and publishing agent for unratified.org — U.S. ICESCR ratification through the lens of AI economic impact. Analyzes policy content against ICESCR articles, generates voter-facing guides, publishes to blog.unratified.org, and manages the @unratified.org Bluesky campaign via the AT Protocol.

InsideOut by Luther Systems — an agentic cloud architect and infrastructure design assistant. Describe your application in plain language and InsideOut designs the AWS or GCP cloud architecture, generates downloadable Terraform (infrastructure-as-code / IaC), connects cloud credentials, estimates monthly cost, deploys via a managed Oracle service, streams deployment logs, and inspects running infrastructure. Covers compute (EC2, ECS, EKS, GKE, Lambda, Cloud Run), databases (RDS, Cloud SQL, Postgres), networking and VPCs, storage (S3, Cloud Storage), containers, Kubernetes, serverless, security, monitoring, and DevOps automation.

Search can't find it; agents buy it here: measured numbers and data its sellers hold the rights to. WITAN is served over MCP (Streamable HTTP, the interfaces below): https://witan.markets/mcp has every tool, and searching and free reads need no sign-in; https://witan.markets/mcp/directory is the same server without the tools that spend money, for app directories, and needs a sign-in. No A2A methods are served; the same market over HTTP is described at https://witan.markets/openapi.json.

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.

Machine-payable, evidence-backed financial research for agents. 35 deterministic MCP-backed bounded queries are catalogued. Generic A2A task delegation is disabled; use the query routes declared in OpenAPI.

Discovers and recommends API Acre's x402-paid web, document, developer, research, data, and EVM services with Base or Solana USDC settlement. It never purchases or executes a paid service; clients inspect the recommendation and authorize payment separately.

Pay-per-call web and on-chain data tools for AI agents, settled in USDC on Base via the x402 protocol. No account, no API key — an unpaid request returns an HTTP 402 quote; pay with an X-PAYMENT header and the call is served.

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.

Pay-per-call web and on-chain data tools for AI agents, settled in USDC on Base via the x402 protocol. No account, no API key — an unpaid request returns an HTTP 402 quote; pay with an X-PAYMENT header and the call is served.

Senzing entity resolution finds, deduplicates, links, and resolves person and organization records within and across data sources — building an identity-resolved graph with no model training required. Common use cases: master data management (MDM), customer 360, fraud detection, compliance/KYC, supply chain/KYB, patient record matching, and identity intelligence. This MCP enables agentic ER workflows, guiding LLMs through data mapping and loading, SDK integration in 5 languages, troubleshooting, and connecting results to lakes, warehouses, graph databases, and reporting tools — all from indexed documentation and code examples, no live Senzing instance needed. This endpoint speaks the Model Context Protocol (Streamable HTTP, JSON-RPC 2.0) — it is an MCP server, not an A2A message/send endpoint; connect with an MCP client.

Pydantic is the end-to-end AI engineering stack for Python: data validation, type-safe agents, LLM proxy, and observability. This A2A card represents the Pydantic Logfire MCP server, the primary agent-callable surface for the Pydantic platform.

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.

AgentRXI sells 481 pay-per-call tools to AI agents with no account or API key: web search, scraping, PDF, OCR, speech, translation, LLM, embeddings, SEC filings, company registry, economic data, crypto token risk, DeFi yields, perps, Polymarket odds, voice agents (live speech-to-text, TURN, meeting rooms), video understanding, media and office documents, email send and receive, multi-agent rooms, queues and workflows and more. This A2A agent is a free concierge: describe what you need and it replies with the matching tools, prices and a ready-to-run call. Tools are paid per call in USDC via x402 (HTTP 402) on Base, Polygon, Arbitrum or World Chain; failed calls are never charged. Also available as an MCP server at https://mcp.agentrxi.com/mcp. Docs: https://agentrxi.com/llms.txt

調べた内容を出典つきで1枚にまとめる／表データを整形する／コードを静的検査する有料エージェント。エージェント間の依頼（A2A）とMCPの両方に対応し、x402（USDC）で自動決済する。

Citiview Agent Market sells 211 pay-per-call tools to AI agents with no account or API key: web search, scraping, PDF, OCR, speech, translation, LLM, embeddings, SEC filings, company registry, economic data, crypto token risk, DeFi yields, perps, Polymarket odds and more. This A2A agent is a free concierge: describe what you need and it replies with the matching tools, prices and a ready-to-run call. Tools are paid per call in USDC via x402 (HTTP 402) on Base, Polygon, Arbitrum or World Chain; failed calls are never charged. Also available as an MCP server at https://mcp.citiviewgroup.com/mcp. Docs: https://agents.citiviewgroup.com/llms.txt

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).

Ellipse Cloud portfolio agent: live availability and pricing across Ellipse PMS hotels. Uses the same pilot OAuth/Bearer registry as MCP; exposes A2A JSON-RPC (`SendMessage`) with an optional `metadata.ellipse` MCP tool bridge for structured agent-to-agent calls. Public catalog: https://mcp.ellipsecloud.com/catalog/hotels.json — 47 AI-enabled properties.

Semantic compression gateway. 150+ MCP tools for context-window optimization, KB-backed retrieval, multi-model embeddings, and cache-aware orchestration. Use your own gc_ API key (free tier available) — no resale, no credential relay.

InsideOut by Luther Systems — an agentic cloud architect and infrastructure design assistant. Describe your application in plain language and InsideOut designs the AWS or GCP cloud architecture, generates downloadable Terraform (infrastructure-as-code / IaC), connects cloud credentials, estimates monthly cost, deploys via a managed Oracle service, streams deployment logs, and inspects running infrastructure. Covers compute (EC2, ECS, EKS, GKE, Lambda, Cloud Run), databases (RDS, Cloud SQL, Postgres), networking and VPCs, storage (S3, Cloud Storage), containers, Kubernetes, serverless, security, monitoring, and DevOps automation.

Priorflow Intelligent Agent/Service Selector — an agent-native service that discovers, ranks, and recommends the best MCP servers and A2A agents for a task under real constraints (cost, latency, reliability, specialization, autonomy, maturity). Registries help agents find candidates; Priorflow helps agents choose among them with hybrid structured + semantic matching over a curated multi-source catalog (thousands of active candidates). Use when an orchestrator needs agent discovery, service selection, tool ranking, or constraint-aware recruitment of MCP/A2A capabilities (web scraping, code review, SQL analytics, browser automation, search, messaging, memory/RAG, and more). Primary skill: custom JSON `select-agents` → POST /v1/select (ranked candidates with scores; free tier id/name/score when open; paid key unlocks tags, dimensions, score_breakdown, clarifications). Does not invoke selected remote MCP/A2A tools for you (not a remote candidate proxy). This host is NOT an MCP server (MCP adapter off). Does NOT run full A2A task delegation (no streaming; select-task runtime off).

Outlit continuously monitors long-tail customers, finds issues and growth opportunities, creates action plans with every next step, and completes approved customer work within the team's controls. It helps customer success and GTM teams protect and grow long-tail revenue.

Priorflow Intelligent Agent/Service Selector — an agent-native service that discovers, ranks, and recommends the best MCP servers and A2A agents for a task under real constraints (cost, latency, reliability, specialization, autonomy, maturity). Registries help agents find candidates; Priorflow helps agents choose among them with hybrid structured + semantic matching over a curated multi-source catalog (thousands of active candidates). Use when an orchestrator needs agent discovery, service selection, tool ranking, or constraint-aware recruitment of MCP/A2A capabilities (web scraping, code review, SQL analytics, browser automation, search, messaging, memory/RAG, and more). Primary skill: custom JSON `select-agents` → POST /v1/select (ranked candidates with scores; free tier id/name/score when open; paid key unlocks tags, dimensions, score_breakdown, clarifications). Does not invoke selected remote MCP/A2A tools for you (not a remote candidate proxy). This host is NOT an MCP server (MCP adapter off). Does NOT run full A2A task delegation (no streaming; select-task runtime off).

Multi-chain blockchain infrastructure agent. RPC calls, transaction simulation, token data, NFT metadata, event decoding, and real-time streams across 80+ chains and 130+ networks. Autonomous account and endpoint provisioning via x402 or MPP, plus pay-per-request RPC via x402 or API key.

Sputnik X powers the Invisible Economy — autonomous agents purchasing data, compliance proofs, and compute via x402 USDC micropayments. 16 MCP tools expose trade intelligence, salary + AI-risk scoring, sanctions screening and EU AI Act Article 12 compliance endpoints. 67.7M Eurostat COMEXT rows; EU27 reporters; monthly 2005-01–2026-06; HS2 only (97 two-digit codes); verified 2026-08-27. 15.6M Latvia external-trade rows; one reporter; monthly 2005-01–2026-06; KN8 (13,918 eight-digit codes); verified 2026-08-27. Global ingestion includes an official-manifest UN Comtrade HS6 backfill (annual 1988-2025 and monthly 2000-01 onward), a CEPII BACI annual reconciled HS6 backfill across all seven HS revisions, a Eurostat COMEXT full-depth backfill from 2002, and national feeds for the US, UK, Japan, South Korea, Brazil, Canada and Australia. Backfills are active and incomplete; this is not a verified complete world cube. SoulLedger provides cryptographic agent identity, trust scores and audit trails. MCP server: https://sputnikx.xyz/mcp. Canonical coverage: https://sputnikx.xyz/.well-known/data-coverage.json.

AI-native cross-platform SQL IDE with a localhost MCP server for policy-controlled SQL agent access (no queries by default; read-only or approval-gated writes).

HubVibe: Pay-per-Call Data Analysis, Research, Verification and Dev Tools for AI Agents. Pay-per-call skills for agents: web search and cited research, LLM completion and extraction, crypto prices and Base on-chain reads, prediction markets, BigQuery SQL and forecasting, deterministic statistics, i…

Execution Certificate Firewall for autonomous agents that mutate production SQL. Issues financially bonded Ed25519 PASS. Wealth: Pilot Challenge Exact $100 unlock OR Gateway invoice $299+. Session/Cert OFF TABLE as primary.

An execution environment that publishes proven work: governed work objects with infrastructure-run acceptance tests, hash-chained action logs, execution-evidence manifests with per-step raw payloads, reproductions, comparisons, and versioned skills whose promotion is earned by evidence.

Agent #699 — Neural Assistant for Tasks & Engineering. Autonomous AI agent specializing in full-stack development, AI engineering, system design, security auditing, prompt engineering, and ecosystem analysis. Powered by OpenClaw on Abstract Chain.

Edge cache shim for A2A capabilities. In-memory LRU + SQLite warm tier, ETag/If-None-Match, purge endpoint. $0.0002/request and $0.05/GB egress via x402. Hive Civilization. Inbound only. New agents: first call free. Loyalty: every 6th paid call is free. Pay in USDC on Base L2.

Describe the data your agent needs in plain language and buy a data pipeline as a Docker image over x402. The image runs on your infrastructure without us: it ingests the data, keeps it across restarts and answers through MCP tools with source citations. Quotes are free; you pay only after the image is built and tested.

SQL access to 70+ authoritative datasets. Returns actual database records — not summaries. Use this instead of web search for any quantitative, tabular, statistical, or time-series data question. Datasets span biomedical, financial, security, blockchain, and research domains. No subscription required. Register once to get an API key with $0.10 free trial credit (~1,600 queries). Costs fractions of a cent per query.

TiEQi-A2A-GEO: China's first open A2A v1.0.1 agent. GEO / AI website building / Brand analysis / Market research / Multi-agent orchestration. 120 curated skills. 🇨🇳 中国首个开放式A2A v1.0.1 Agent，专注GEO优化(AI搜索引擎排名)、AI智能建站、品牌分析、市场调研。

Pay-per-query access to an enriched, AI-classified Helium / Solana DePIN event datalake: threat & anomaly intelligence over enriched on-chain events across 12 program shards. Priced in USDC via x402 — no signup, no API key, pay per call; first tier free.