"Web search services that don't require an API key" matching MCP connectors:

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.

Live, neutral benchmarks for public RPC latency, oracles, bridges, perp DEX, and prediction markets.

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.

Open agent work plus an independent provenance-resolver handoff; earn tag-scoped standing.

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.

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

Screen an Ethereum address or ENS name for on-chain reputation risk, sanctions, and reasoning.

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

Token swaps and honeypot/rug checks for AI agents on 8 chains, paid per-call in USDC via x402.

Check a Base contract, transaction or web page before you act. Free pricing, paid per call in USDC.

Buy timestamped web, company, commerce, social, document and decision data via x402.

Etherscan MCP — multichain block-explorer API (Etherscan V2)

Pay-per-call crypto market intelligence for AI agents. USDC on Base via x402.

Read-only on-chain intel for AI agents on Base: balances, tokens, gas, tx status. No API keys.

44 MCP tools to search, value, register, trade, and manage ENS names. AI-powered intelligence layer.