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

Polymarket, Manifold, Metaculus compared: one fair probability per question. No API key needed.

Measured share of answer for 24 crypto and Web3 brands. An open dataset, not an audit of your site.

Exit-cost estimates, depth concentration, liquidity tiers, and sealed records; no commodity futures.

Fourteen paid x402 and MPP tools for web data, payment preflight, audits, DeFi, and work discovery.

The Brain Layer for AI Trading Agents — quant calls + cross-venue arb across perp venues via MCP.

Enumerate and inspect PubFi capabilities, then execute an exact selected route.

Identity infrastructure for the AI economy. Confirms if someone is known; returns inferred traits.

Is a wallet frozen by Tether/Circle? Free freeze checks + full history, screening & KYT. 9 chains.

Pre-transaction token risk checks for autonomous agents. Read-only; never signs or moves funds. Paid per call in USDC via x402. Supporting Base, Solana, Ethereum, Arbitrum, BSC and HyperEVM

SEC/XBRL issuer intelligence for crypto public companies via MCP, OpenAPI, x402, and MPP.

Settlement layer for AI agent commerce. 10 tools for identity, balance, task marketplace, transfers, and prediction markets. Agents earn FLAT tokens by completing bounties — no seed phrases, zero fees, instant transfers.

Teardrop is the native economic layer for AI agents, providing a robust suite of tools for multi-chain portfolio tracking, DeFi yield analysis, and gas estimation. It enables autonomous agents to securely find Web3 data and manage micro-payments on-chain with zero human intervention.

Cross-venue Polymarket+Kalshi arbitrage: resolution mismatch, void risk & settlement divergence.

Universal pay-per-call tool API for AI agents. Web search, price feeds, hive memory, LLM routing, code sandbox. Free tier (10 calls/day, no signup). x402 payments on Base + Solana.

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.

AI inference via MCP — pay per request with Solana USDC through x402. No API keys.

Real-time financial intelligence MCP server for crypto public companies. Provides covenant stress analysis, alpha signals, peer ranking, risk distribution, SEC XBRL fundamentals, and daily changes. x402 micropayments on Base USDC. First 5 calls free.

Solana token risk-scoring MCP server for AI trading agents with insider wallet cluster detection.