"A server for exploring information about quantum physics or quantum-related topics" matching MCP servers:

Free x402 endpoint checker plus paid report and metadata tools. Remote MCP server for agents. Written by AI named Nock, not a human.

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.

An MCP server that wraps the Check Payroll API, providing 263 tools for managing companies, employees, contractors, payrolls, tax configuration, and more.

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.

MCP server exposing a fictional payment domain as tools, resources, and prompts, enabling reasoning over transactions, payment hubs, services, and system health.

Talk to your DeonPay merchant account from any MCP-compatible AI host. Enables reading transactions, creating payment links, inspecting subscriptions, and more.

Generate crypto QR codes (BTC, ETH, SOL, USDC, USDT, EURC) and manage payment sessions from Claude Desktop or any MCP client. Non-custodial, free.

Exposes all 379 Invoice Ninja v5 REST API endpoints through three consolidated tools (list, describe, call), enabling full invoice management and business operations via natural language.

Create invoices from any MCP client via the Invovate API — compute totals and generate PDF, JSON, or UBL invoices in 11 languages. Exposes four tools: calculate_invoice_totals (no API key needed), generate_invoice_pdf, generate_invoice_ubl, and get_invoice_capabilities.

Enables issuing invoices, proformas, and delivery notices, collecting payments, submitting e-Factura to Romania's SPV, and querying reference data on Oblio.eu through natural language from MCP clients.

An MCP server that exposes Alipay AI Pay capabilities to AI agents, enabling skill discovery, payment integration guides, and merchant onboarding workflows via Alipay's payment APIs.

Enables AI agents to directly operate ChainPay cryptocurrency payment system, including order creation, balance checks, and withdrawals.

Marketplace MCP for paid HTTP APIs. Pay per call in USDC on Base via the open x402 standard — non-custodial. 13 tools for discovery, buying, and publishing APIs.

Enables AI agents to autonomously pay for Xiaohongshu note details, user notes, and wholesale pricing data using USDC micropayments on Base via x402, with automatic payment signing, retries, and configurable spending limits.

MCP server for the Monei API that gives AI agents access to wallets, transfers, crypto sends, swaps, offramp, and bill payments through natural language.

Enables AI agents to discover, negotiate, and settle payments on the AGIRAILS network directly from MCP-compatible editors, supporting escrow for complex jobs and instant x402 payments.

Lets AI assistants shop at UCP-enabled merchants through tools for discovery, checkout, discounts, fulfillment, and payment.

Enables interaction with the Yugo Payments API to manage payins, payouts, and accounts through auto-generated MCP tools.

Enables AI assistants to parse, validate, send, and inspect X12 EDI documents via the SignalEDI Core API, with optional QuickBooks integration and a demo mode for keyless local testing.

Read-only MCP server for the RareCloud API, enabling AI agents to list servers, browse the catalog, check billing, and plan deployments.