"A tool for finding information about Zotero, the free reference management software" matching MCP servers:

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.

Enables AI coding assistants to log billable hours into the Keeping time-tracking service via MCP tools, with dry-run protection for all write operations.

Create free, no-signup invoices from your AI assistant — the create_invoice tool returns a link that opens blankinvoicemaker.com pre-filled, ready to download as a watermark-free PDF.

An MCP server whose tool invocations are metered and charged over x402, plus a paying-proxy reference client that lets any standard MCP client use the paid tool without knowing x402 exists.

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 remote MCP server on Cloudflare Workers with Stripe paywall, offering a free dice tool and a paid premium report tool.

x402-trust gives AI agents a "check before you pay" layer for the x402 ecosystem.

A template for building MCP servers with a built-in paywall gate that offers free local execution and premium server-side execution via Stripe and x402 payment lanes.

MCP server for real FDM 3D-printing slicing, quoting, and design-for-manufacturability analysis via the FabTally API, supporting 12 printer profiles and 12 materials. Includes free discovery/printability tools and paid slice/quote/orientation tools settled via x402 (USDC on Base).

Discover and pay for APIs and MCP tools per call over Bitcoin Lightning (L402): search the bolthub marketplace, preview prices, and pay from your own wallet (LND, NWC, LNbits) with hard budgets, prepaid credit, scoped sub-agent delegation, and verifiable receipts. Non-custodial and works without a wallet for search and free tools.

Enables AI agents to manage a fictional B2B workspace SaaS (Tessera) with tools for ticketing, invoicing, customer management, and trial extensions, featuring a human-in-the-loop confirm pattern for safety.

Unofficial MCP server for Oblio.eu accounting software enabling natural language interaction to create invoices, manage documents, collect payments, query nomenclatures, and submit e-Factura to Romania's SPV system.

Payment firewall for AI agents: a signed, independently verifiable verdict on every money-moving action. Blocks wrong/lookalike payee, over-cap, and duplicate-invoice (BEC) fraud before money moves — anyone can verify a verdict against the public JWKS. Free, local-first, non-custodial.

Enables issuing invoices, proformas, and delivery notices, collecting payments, submitting e-Factura to Romania's SPV, and querying reference data on Oblio.eu through natural language from MCP clients.

Enables querying MRR, churn, and revenue from Stripe, Gumroad, and Lemon Squeezy directly inside Claude, allowing natural language questions about business metrics.

Identity infrastructure for the agent economy. Mint an agent ~handle in two free calls with no human account, then verify anyone and read inferred traits under the consent the person set in advance.

MCP server for a live x402 payment gateway on Base (USDC). Lets AI agents discover, preview for free, then pay per call — with prepaid gasless payments, signed receipts, and delta delivery.

Enables interaction with the Crowns game API as MCP tool calls, including x402-based payments.

Client-side MCP wrapper for Orisha Data's public x402 endpoints, providing free preview tools and paid market data access via x402 payments.