"Using an AI Agent for Structured Search and Traversal in a Neo4j Database" matching MCP servers:

AI Agent Hub is a pay-per-call API platform for AI agents Every call is billed automatically in USDC using the x402 protocol - there is no API key, no account, and no signup. Agents get instant access to data queries, file storage, and ad impressions, paying only for what they actually use. The same tools are also exposed natively over MCP, so any MCP-capable agent can discover and call them

MCP server that provides tools for retrieving transaction context and recording AI decisions or creating human reviews for payment risk exceptions. Enables LLM agents to handle exception transactions in a hybrid payment-decisioning workflow.

Pay-per-use semantic web search for AI agents. Powered by SearxNG, agents pay in sats via Lightning Network micropayments — no API keys required.

Enables an AI agent to act as a merchant, selling catalog items and issuing USDC invoices with cross-chain payment support via Arcorapay.

CLI and local stdio MCP payment runtime for AI agents on macOS Apple Silicon. Supports x402 offer inspection and payment preparation, with signing and execution requiring foreground owner approval.

Enables AI agents to check their wallet address and USDC balance, preview the cost of an x402 call, and pay for API requests in USDC on Base without an account or API key. Spend caps, allow-lists and blocked contracts are enforced in code before anything is signed, so a prompt injection cannot bypass them.

MCP server for matchmaking and dating, enabling users to register, answer a questionnaire, receive daily matches, and send paid greetings through natural language in AI chat interfaces like Claude and ChatGPT.

Pay-per-call USDC payment proxy for AI agents. Issue scoped Pay Tokens with hard spending caps and auto-journal every charge to freee / Money Forward / QuickBooks.

Official Dodo Payments MCP servers - dodopayments-api for live payments, subscriptions, customers, products, refunds, license keys, and usage-based billing (browser OAuth, no API key needed) and dodo-knowledge for semantic search over Dodo Payments documentation.

MCP server for creating and fiscalizing invoices via solo.com.hr API. Enables AI agents to generate invoices, retrieve invoice details, list invoices, and check next invoice number.

MCP server that checks an x402 paid endpoint before an agent pays it, and checks afterwards that the receipt opens to exactly one real on-chain settlement. Two tools, no account, no API key.

Quote, book, and track real LTL, FTL, cargo van, and box-truck freight through the Warp network - 20 tools, in-chat login, Stripe-charged bookings, and real carrier dispatch. Quoting is keyless; booking needs a free Warp account with a card on file.

An MCP server that lets your AI coding agent (Claude Code, OpenClaw, Codex, Cursor, etc.) discover and pay on-chain agents registered on ERC-8004, using Coinbase's official x402 protocol. No smart account. No bundler. No relay. Just your EOA, an HTTPS request, and an automatic 402 → sign → retry flow.

The MCP gateway that lets any AI agent discover and pay metered APIs on Base or Solana — without the user wiring payments themselves.

Enables Claude to access, analyze, and optionally modify invoices, installments, receipts, clients, and financial reports via the Fatture in Cloud API v2, with read-only default and multi-layer safety.

Enables agents to hold a local Base USDC wallet, receive funds, make bounded x402 payments, prepare seller registration, and recover Voidpay Marketplace results over stdio.

Spending limits for AI agents. Create budgets, enforce limits, track spend across x402, cards, MPP, or any payment rail.

Fully autonomous, crypto-monetized MCP server on the Base network. Provides premium smart contract auditing, patching, and token data arbitrage using the x402 micro-transaction protocol.

NexaLayer MCP Server — a Model Context Protocol server that lets AI agents create and manage dynamic and static proxy sessions with budget guardrails.

Credit and payments for AI agent developers — over MCP. No crypto required