"An overview of knowledge graphs" matching MCP servers:

The first commercial implementation of HTTP 402 Payment Required for creator content. AI agents discover music, video, and text catalogs as pre-indexed Pockets (list_pockets, search_pockets — free, no key) and pull licensed content per-use through a 402 paywall. Tiered per-pull pricing by content type; 85% of every pull pays the rights holder instantly, with attribution and an audit trail.

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.

PayCheck is an MCP server that checks a planned payment before an agent pays.

Lets an AI agent hire and pay a verified human: post real-world tasks (voice, observation, judgment) and pay in USDC via a non-custodial x402 auth-capture escrow on Base, budget frozen at deploy. Humans verify their X identity before submitting.

An MCP server for the SmartBill Cloud API. It lets an MCP client issue and manage Romanian invoices, proformas and payments, download document PDFs, and read VAT rates, series and stock levels.

A read-only MCP server for the open-banking.io PSD2 API that lets AI agents query personal bank balances and transactions via natural language, with zero-knowledge encryption ensuring all sensitive data is decrypted in-process and never exposed to third parties.

Verified pay-per-call catalog: factual checks of x402 agent services for AI agents.

MCP server that lets a chatbot browse eSIM plans, sign in, prepare quotes, and execute wallet or card purchases on an existing eSIM platform, with safe typed tools.

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 that gates API calls to AI agents using proof-of-work (free) or Lightning payment (3 sats), providing challenge, verify, and status tools for per-call authentication without accounts.

Enables agents to discover and call thousands of live agent tools with known prices, claim escrowed tasks, and settle payments via x402.

Enables AI agents to draft AP-style press releases from a product URL and publish them to a public newsroom page, or distribute them across a newswire to hundreds of news, TV and radio sites, with status tracking for wire orders. Paid calls are settled per request in USDC on Base via x402 from the user's own wallet, defaulting to quote-only mode with spend caps and confirmation tokens.

This is an MCP server for the BillingServ API. Once it's set up, your AI assistant can look up customers, invoices, orders, packages, and reports straight from your BillingServ installation

Enables coding agents to create and look up crypto payments over stdio, returning checkout links, payment statuses, paged payment lists, and receivable currencies, with real payments gated behind an explicit opt-in environment flag.

Enables MCP clients to access all endpoints of an x402 gateway by paying real-time microtransactions (USDC on Base) per API call, with automatic tool discovery and spend guardrails.

Enables issuing credit notes and credit memos against an invoice or standalone as revisable drafts that can be finalized into frozen numbered documents, then rendered as Markdown or printable HTML with totals broken down by currency, reason and month. All amounts are handled as integer minor units and all data stays local, so nothing is sent anywhere.

Exactly-once execution for irreversible agent actions: an agent claims the right to run an effect, and a retry after a lost response returns the sealed result instead of charging again. 12 tools over stdio, including a gateway mode where the agent holds a single-use ticket and never the provider key.

Merchant-side MCP server for agentbank that lets merchants read their own orders and live Curless wallet balance from an MCP client such as Claude Desktop.

Enables AI assistants and agents to vet a stablecoin or x402 payment before it is sent, returning an approve, hold, or reject decision from instant rule checks and an optional locally-run risk model. Fails closed, so malformed input or an unreachable model yields a hold rather than an approval.

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.