"Examples of online search and data retrieval services" matching MCP servers:

Pay-per-use AI security and research tools for autonomous agents on Base, enabling honeypot detection, risk assessment, wallet analysis, and yield optimization via the x402 protocol.

Enables AI agents to fetch live multi-chain portfolio, token info, gas prices, and token prices across Ethereum, Base, Polygon, Arbitrum, and Optimism with a single call. No API key required.

This MCP wraps Bitrefill public API to allow agents to search for products and shop using cryptocurrencies like Bitcoin, Ethereum, Solana, and many more.

Monero/Zcash payment webhooks + DeFi liquidation & Ethereum builder data over MCP. Free tier; x402.

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.

MCP server that lets AI agents search the substreams.dev package registry.

Enables AI agents to fetch crypto market and on-chain data, including prices across venues, token facts, OHLC candles, market overview, DeFi TVL, and wallet balances, with two free tools and the rest paid per call in USDC on Base via x402.

Enables MCP-capable AI agents to access pay-per-call Solana data such as health, token prices, account balances, transactions, and trending DEX pairs, with automated x402 USDC settlement and no signup or API key required.

Enables MCP-capable AI agents to make pay-per-call Solana data requests (snapshots, risk checks, token reports, health, balances, transactions, trending pairs) with automatic USDC settlement over x402.

Read-only MCP server for discovering and ranking on-chain agents on Stellar mainnet via natural language search, reputation probes, and profile lookups.

23 agent tools: DEX token prices, liquidity, slippage, gas and arbitrage across BNB Chain, Polygon, Arbitrum, Base, Avalanche and Optimism, plus geocoding, weather, web search, URL-to-Markdown, RSS, IP geolocation, holidays, GLEIF LEI lookup and the US Treasury yield curve. 22 are free with no API key, wallet or signup. One paid cross-DEX spread tool pays from your wallet, with hard spend caps.

MCP server for Crypto APIs Block Data product. Get block details by height or hash for EVM, UTXO, and XRP blockchains.

Signed, outcome-verified smart-money data for Polymarket: which wallets actually win, scored from real on-chain settlement (95% Wilson lower bound over resolved markets) and ed25519-signed so an agent can verify it offline. Whale trades, smart-money consensus and wallet track records, paid per call in USDC over x402, with no account and no API key.

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

Enables AI assistants to access AnChain.AI blockchain intelligence APIs for risk assessment, sanctions screening, and transaction analysis on blockchain addresses and transactions.

MCP server for Crypto APIs Transactions Data. Enables lookup of transaction details by hash across EVM, UTXO, Solana, XRP, and Kaspa blockchains.

Enables AI agents to discover, pay for, and invoke x402-priced services such as document OCR, document analysis, media transcription, remote browser sessions, and receive-only email inboxes using USDC on Base, with no API keys and receipt-backed results.

Made-to-order data for AI agents via x402 micropayments on Base. Describe a need in plain language, get a custom quote, pay per call. No signup, no API keys. HTTP + MCP transports. 5 tools.

Premium research articles for AI agents with x402 payment on Base network.

Enables querying public Bitcoin network data including fees, mempool status, hashrate, transactions, address stats, and Lightning network information without requiring API keys.