"Free Graph and Network Visualization Tools (No API Key Required)" matching MCP servers:

Enables AI agents to discover, pay for, and retrieve receipts for external APIs via USDC micropayments through the SynapseNetwork Gateway, supporting stdio and Remote MCP.

Provides current weather conditions and 7-day forecasts for any location worldwide, covering temperature, humidity, wind, and precipitation, with pay-per-call micropayments via x402.

MCP server for Brazilian data lookups (Pix codes, CEP, CNPJ) and web rendering tasks (Markdown, screenshots, PDFs) via a paid HTTP API with x402 billing.

MCP server for deterministic financial transactions, providing tools to fetch account balances, check blocked PIX keys, and execute atomic PIX transfers with integer-cent precision.

Credit and payments for AI agent developers — over MCP. No crypto required

MCP Server for the LINE Shopping API, enabling AI agents and tools to interact with LINE Shopping data and operations via the Model Context Protocol.

Kill switch + spend guard for AI agents that spend money: one policy, one sub-second freeze, and one signed audit ledger across every wallet vendor at once (Coinbase, Turnkey, Openfort + cards). Tools include a pre-flight request_spend guard, freeze, apply_policy, ledger, and x402/AP2 payment-mandate guards — free self-serve key, no account.

A comprehensive Model Context Protocol (MCP) server that provides complete access to the Recharge Storefront API endpoints. Enables AI assistants to manage subscriptions, customers, orders, and billing through a standardized interface.

A Model Context Protocol (MCP) server that provides testing and debugging tools for Stripe integrations, including test clock management, customer and product management, and subscription testing.

An MCP server for Nexi POS payment operations, enabling creation of purchases and refunds, polling payment states, confirming transactions, and recovering unconfirmed transactions.

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 providing payment validation tools and resources, including card number Luhn checks, card network detection, and IBAN validation, with no network calls required.

Pay-per-use semantic web search for AI agents. Powered by SearxNG, agents pay in sats via Lightning Network micropayments — no API keys required.

Enables AI agents to interact with the BulkClix platform for SMS, OTP, airtime, mobile money, bank transfers, data bundles, KYC, contacts, and account management via natural language.

Provides real-time stock quotes including price, change, volume, market cap, and company name for major US and international exchanges, with pay-per-call access via x402 micropayments and no API key or signup required.

Enables AI agents to access real-time financial data, news, and web reading through a single MCP endpoint with zero installation.

A local MCP server that exposes the Splitwise API as tools, enabling conversational management of expenses, groups, and friends. It runs entirely locally over stdio with no hosting required.

Enables sending transactional emails with text or HTML body, delivery status, and message ID via Resend. Pay-per-call using x402 micropayments (USDC on Base L2), no API key or signup required.

Enables AI agents to pay for services in DigiByte/DigiDollar on testnet via the x402 pay-and-retry pattern, with spend limits and security policies.

Connects AI assistants to Quaderno's tax compliance engine, enabling tax calculation, tax ID validation, and invoice creation via natural language.