"Examples of MCPs (Microservices Communication Protocols) That Do Not Require API Keys" matching MCP connectors:

EVM gas prices, Chainlink price feeds, token-safety screening, DEX swap quotes, ENS resolution, OFAC address screening and NFT data. Pay-per-call in USDC on Base via x402 — no signup, no API keys.

Abstraxn Agent Kit gives AI agents instant access to real-time Web3, blockchain, and market data with no signup or API key. Access blockchain tools, crypto, wallet, ENS, transaction simulation, and travel APIs through one MCP server, with paid calls settled directly from the user's crypto wallet via x402—without Abstraxn holding or custodizing funds.

Open AI Visibility Index for crypto and Web3. Weekly share-of-answer measurements for 24 tracked brands across ChatGPT, Perplexity and Gemini, from a frozen versioned prompt panel. Five read-only tools: full index, per-brand lookup, brand list, complete measurement history and methodology. No auth, no API key. Data is CC BY 4.0 with a permanent archive of every weekly snapshot, so any figure can be verified independently.

See what actually settles on x402: wash-adjusted volume, payTo checks. Free, no key, no signup.

Mocap, rehab biomechanics, threat intel, fleet vision. 21 MCP tools, 10 free. x402/USDC paid.

Search, buy, and manage domains, DNS records, orders, and NFSC balance on Namefi.

Search scored onchain agent frameworks, MCPs, wallets, tools, and live agents.

Free, keyless MCP server with 50 read-only blockchain tools for Bitcoin, Ethereum, and Mezo. No installation, no API key required -- just add the URL to your MCP client and start querying balances, transactions, blocks, ENS names, ERC-20 tokens, smart contracts, and more. Runs on Cloudflare's global edge network via Streamable HTTP. All tools are strictly read-only and stateless.

Plain-English decode of any Base mainnet transaction: strict JSON, risk flags, no LLM.

Free, keyless MCP server with 50 read-only blockchain tools for Bitcoin, Ethereum, and Mezo. No installation, no API key required -- just add the URL to your MCP client and start querying balances, transactions, blocks, ENS names, ERC-20 tokens, smart contracts, and more. Runs on Cloudflare's global edge network via Streamable HTTP. All tools are strictly read-only and stateless.

Feed of x402/L402 services newly listed on 402index.io within a recency window (candidate #8, manual

Live operational + integration registry for Bittensor subnets: APIs, schemas, health.

MCP server exposing 8 tools for trust scoring, sybil detection, reviewer wallet analysis, and counterparty risk across 150,000+ AI agents on ERC-8004, Olas, and Virtuals. Streamable HTTP, JSON-RPC 2.0, no API key required.

Risk-adjusted stablecoin yield ranks for other agents. Research only. Never holds keys or executes.

Twelve tools: token, wallet, contract and site security. Two free, the rest $1 in USDC over x402.

Zero-install remote MCP server for proof-of-existence file attestation.

AI price forecasts, whale flows, market sentiment and prediction signals. 18 tools free, no account.

Solana memecoin rug check for trading agents: pump.fun launches, calibrated rug risk, wallets, KOL.

Onchain loyalty MCP on Base: programs, mint, rewards, vouchers for AI agents.

x402 game: take the crown, each take raises the next price 1.5x. hill_status is free.