"A search for free items, services, or resources" matching MCP servers:

Enables AI agents to access DDG's payable services including checkout/payment conformance, MCP/tool security audits, agent-discovery repair, and buyer-agent smoke probes, with structured payment challenges.

Enables agents to access production-grade paid MCP tools with real on-chain x402 v2 settlement, including EVM wallet risk scoring, payload normalization, and facilitator discovery, all discoverable via Bazaar-compatible metadata.

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

Read-only MCP server that performs deterministic local preflights of agent-payment boundary documents and x402 v2 PaymentRequired JSON, and prepares unsubmitted public quote-request drafts without network calls or fund movement.

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.

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 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.

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.

Enables MCP-capable agents to search the curated gold-402 directory of x402 services, probe any endpoint for valid 402 payment terms, and optionally purchase a human editorial verdict for a resource.

MCP server exposing a fictional payment domain as tools, resources, and prompts, enabling reasoning over transactions, payment hubs, services, and system health.

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.

Trust infrastructure for the machine economy. Gives AI agents non-custodial smart accounts (ERC-4337), x402 payments, on-chain reputation via ERC-8004 trust registry, and service discovery. 8 tools: create accounts, transfer, check balances, pay for x402 services, publish/discover services, manage payment agreements, and send encrypted messages.

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

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.

Enables agents to search a verified directory of machine-payable services, inspect service and wallet reputation, and get pre-payment checks before spending.

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.

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.