"Understanding RAG (Retrieval-Augmented Generation or related topics)" matching MCP servers:

Generates compiled Flutter apps from JSON Product Requirements Documents. Exposes endpoints for PRD validation, schema, payment terms, and build status.

Enables AI agents to call paid APIs and settle HTTP 402 payment challenges with USDC on Base, without private keys ever being involved.

Keyless crypto payments for AI agents. One MCP call turns any wallet address into a non-custodial crypto payment link or tip jar, no API key and no account, with funds settling straight to your wallet at a 0% platform fee (USDC/USDT, BTC, LTC, DASH, DOGE, ZCASH).

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.

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.

An MCP server that exposes the pacs008 ISO 20022 FI-to-FI Customer Credit Transfer library as tools for AI agents and assistants, enabling generation, validation, and parsing of pacs.008 credit transfer XML messages.

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.

Provides AI agents with SSRF-protected URL intelligence and 32 paid REST/MCP tools, plus a free catalog search, with payments in USDC on Base Mainnet.

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.

Enables interaction with the PayHere payment gateway via MCP, allowing payment retrieval, refund issuance, checkout payload generation, and signature computation/verification.

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.

Provides access to 70 paid APIs as MCP tools with per-call and session budgets, paying via x402/USDC on Base without requiring an account or login. Includes a built-in allowlist of hosts and safe defaults to prevent unintended payments.

Domain registration for AI agents. Check availability, buy domains (Stripe or x402 crypto), and auto-configure Cloudflare DNS - all without leaving your coding session.

Pactus is an MCP server for parsing and validating ISO 20022 payment messages directly from chat. It exposes nine tools that let AI assistants inspect or validate pacs.008, pacs.002, pain.001, and camt.053 messages — the message types at the centre of the CBPR+ migration — without leaving the conversation.

Model Context Protocol (MCP) server for Brazilian Electronic Invoicing (NF-e / NFC-e, modelo 55/65, schema 4.00). Provides CPF/CNPJ validation tools, with NF-e/NFC-e generation and SEFAZ integration planned.

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

Enables agents to request payment authorization against signed human mandates, enforcing policy-as-code limits and returning a decision (authorize, challenge, or deny) without moving funds.