"A search for academic or research papers" matching MCP servers:

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

Universal HTTP 402 Micropayment Protocol & Autonomous Economic Settlement Engine for AI Agents on Base L2.

Connects MCP clients to a telephony account so users can manage phone numbers, SIP accounts, routing, SMS, calls, and billing in plain language. It exposes search, schema lookup, and execute tools to run permitted API operations, with confirmation required for paid or destructive actions.

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.

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.

A pre-payment safety gate for x402 that screens payment metadata for PII, enforces spending policies, and detects replay attacks before signing.

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

A paid MCP server that lets AI agents send SMS messages to US phone numbers via x402 micropayments, with automatic compliance and opt-out handling.

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 for the Gravv payments API that lets AI assistants onboard customers, run KYC, open accounts, move money, issue cards, and exchange currency, with built-in documentation search and safety confirmations for money-moving operations.

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.

Official Dodo Payments MCP servers - dodopayments-api for live payments, subscriptions, customers, products, refunds, license keys, and usage-based billing (browser OAuth, no API key needed) and dodo-knowledge for semantic search over Dodo Payments documentation.

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.

A local stdio server that lets coding agents build and verify a merchant payment integration against a sandbox, creating and cancelling invoices, simulating payment outcomes, checking invoice status, and validating webhook signatures. It also serves embedded docs as resources and refuses live or payout keys, keeping all work out of production paths.

Enables AI agents to search marketplace listings, place escrow-protected purchases paid in Nano, track orders, and retrieve signed receipts.

Provides a non-custodial USDC wallet on Base for AI agents, with human-in-the-loop approval for every payment.

Unified gateway for ISO 20022 message families, providing meta-tools to search, describe, validate, generate, and parse financial messages.

Enables MCP-wired agents to fetch live, historical, or proof-backed Base-mainnet asset prices signed with ML-DSA-65 and anchored to Hedera, automatically handling x402 USDC payments; it also lists the provider's available x402 services.