"Finding solutions for computational mathematics or engineering problems" matching MCP servers:

Enables retrieval of customer records and triggering refunds via MCP tools, supporting both stdio and streamable HTTP transports.

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.

Provides a three-layer payment firewall for AI agents, enabling identity verification, risk screening, and execution authorization with on-chain policy enforcement for secure and auditable transactions.

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

Universal x402 buyer agent — discover, pay for, and call any x402 paid API endpoint from Claude Desktop, Cursor, or Claude Code with automatic USDC payment via AgentCash.

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.

MCP Server for AI agents to discover and call pay-per-request APIs via EntRoute. Give Claude, Cursor, Windsurf, or any MCP-compatible agent access to 350+ verified x402 API endpoints across 110+ capabilities — DeFi prices, web search, prediction markets, news, 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.

A local MCP server that integrates ProofJSON to assess invoices before payment, providing allow/review/block decisions with confidence scores and verification capabilities.

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.

Lets AI agents discover, pay for, and call any HTTP API per request using USDC, with gasless nanopayments and no API keys or accounts needed.

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

Read-only MCP server for the Swiss eBill portal, enabling users to list bills and download invoice PDFs via an authenticated browser session. It cannot approve, release, or pay anything.

Enables building client statements of account from existing invoices, credit notes, and deposits, with aged outstanding balances, PDF/plain-text output, and drafted payment chasers at friendly, firm, or final levels.

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

Enables AI assistants to access the Billingo v3 invoicing API through MCP, providing 49 read/write tools for managing invoices, partners, and related data over stdio or HTTP transports.

Enables AI assistants to operate the Ribbo recurring billing API, allowing them to manage subscriptions, check entitlements, refund payments, charge immediately, and generate payment or renewal links.

Enables AI assistants like Claude Code or Cursor to interact with a PNLCS billing panel, querying and managing clients, invoices, orders, tickets, and transactions via natural language.

A read-only MCP server that lets AI clients query real financial data (bank, credit card, loan, brokerage) via Plaid or Teller, offering tools for balances, transactions, investments, liabilities, identity, income, and debt analysis.

Enables AI agents to buy, hold, and transfer CPI-pegged FLAT stablecoin without wallets or gas. Provides tools for earning through tasks, trading, and managing balances via MCP.