"Understanding and Using JSON" matching MCP servers:

Reads and validates any European e-invoice a business receives — XRechnung, UBL, CII, ZUGFeRD/Factur-X PDF, Peppol BIS 3, FatturaPA, KSeF FA(3) — into canonical EN 16931 JSON with plain-language fix hints in EN/DE/PL/IT/FR, plus PDF, CSV and DATEV export. Nothing is stored; works without a key on a small daily quota.

A local, read-only stdio MCP server that lets a Grok Build CLI agent check how much of its weekly SuperGrok / Grok Build usage pool is left, when the period resets, and its Extra Usage cap via tools like get_budget. It reads the existing grok login session and returns per-product figures as JSON, mirroring the TUI /usage screen, so agents can pause before expensive work when quota runs low.

Enables AI agents to create and manage sellable listings, handle orders, and integrate Stripe payments through natural language using ListBee's API.

MCP server that gives AI agents paid tools to de-risk costly actions: dependency vetting, x402 endpoint verification, JSON repair, and URL reading. Fronts the Guard HTTP API at guard.fabtally.com.

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 MCP clients to access Monobank's open API for exchange rates, account and jar balances, and statements, as well as set webhooks, using natural language tools.

MCP server providing Polymarket weather-market bucket-transition signals for AI agents, with free city/signal inspection tools and paid signal bundles via USDC on Base using x402.

Provides currency conversion using the Wise API, supporting real-time and historical rates with caching and cross-rate calculation.

Enables AI agents to discover, inspect, and pay for paid HTTP and MCP services using USDC on Solana with a self-custodial wallet.

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 FastSpring e-commerce platform for managing orders, subscriptions, and accounts through natural language using the Model Context Protocol.

Enables AI clients to check an application balance and preview or send bulk SMS and airtime, either through a hosted OAuth connection that needs no local install or via a self-hosted stdio/Cloudflare Workers deployment using your own credentials. Sending is preview-only by default and gated behind environment, recipient allowlist, and mutation opt-in settings.

Connects Claude to the customer side of Housecall Pro, letting you view estimates and invoices, check company details, and decline estimate options using the link your contractor sent.

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.

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.

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.

Enables AI agents to call x402-gated APIs using a central credit balance, abstracting away blockchain complexity and payment proofs. It provides tools to fetch data from payment-required endpoints, check usage balances, and simulate transaction costs.

Enables Claude to interact with the Open Finance Brasil APIs, allowing users to query accounts, balances, transactions, credit cards, PIX keys, initiate PIX payments, and view investments across supported Brazilian banks using natural language.

Enables AI agents to discover, evaluate, and purchase live data from the Macaroon Network marketplace using semantic search, metadata checks, and Bitcoin Lightning payments.