"A GitHub MCP server for browsing and understanding source code without requiring an API key" matching MCP servers:

Free DEX aggregator API that returns executable swap calldata across 46 EVM chains. No API key required. Single GET request returns ready-to-sign transactions for any token pair.

Eight crypto and DeFi data tools for AI agents: prices, gas, one ParaSwap route quote, GoPlus token security and top-holder samples, DefiLlama yields, Hyperliquid/dYdX funding, and observed wallet balances. Inspect prices free; pay 0.001–0.008 USDC per call on Base through x402. No API key or subscription.

Enables agents to access live DeFi, social intelligence, risk, and API documentation tools with a caller-supplied API key.

Bitcoin data for AI agents. Pay-per-query via x402 micropayments. No API keys. No subscriptions. No tokens.

Enables autonomous Web3 security monitoring by watching honeytoken decoy private keys in the mempool to detect intrusions and trigger tripwire alerts. It also supports smart contract auditing, callgraph verification, and DeFi vulnerability triage through MCP.

MCP server providing real-time crypto prices (Chainlink + Binance), Polymarket prediction market data, deep web research, and JS-rendered web scraping. All services available via x402 Solana micropayments.

55+ pay-per-call tools for AI agents over MCP: live telemetry, blockchain/on-chain checks, environmental, transit, finance, and network utilities. No API key or signup — agents pay per request with x402 USDC micropayments (Base and Solana).

Enables AI assistants to query blockchain chain data, including chain details, RPC endpoints, and chain relationships, through a Model Context Protocol server.

Cross-chain cryptocurrency swaps via Chainflip. Get quotes, execute swaps, and track progress. No API key required to get started.

Enables monitoring honeytoken decoy private keys for mempool activity, detecting and alerting on potential intrusions.

Gives Claude access to Alchemy blockchain APIs by loading all API specs at startup and providing two tools: search and execute. Enables querying NFTs, token balances, transactions, and more via natural language.

Non-custodial crypto swaps for AI agents: Solana (Jupiter) + 7 EVM chains (KyberSwap), 1288+ assets, cross-chain routing, priority-fee oracle, Hyperliquid perps. Returns unsigned transactions — your wallet signs, no API key, no KYC. Hosted at https://swaptitan.net/mcp

MCP server for cross-chain bridging, enabling AI agents to find routes, estimate costs, check risks, execute transfers, and track status across blockchains.

43 x402-enabled API tools — DeFi, wallet security, AI/ML, developer tools, SEO. Pay-per-call USDC on Base via x402 protocol.

An MCP server that enables LLMs to query DAOs, proposals, and voting data from Tally's blockchain governance API across multiple networks.

MCP server for decoding and inspecting x402 payment headers and requests. Remote endpoint: https://lumenworks-x402-decoder.onrender.com/mcp

A Model Context Protocol server implementation that provides endpoints for wallet-based authentication, cluster management, and name registration services.

Provides counterparty risk checks for any EVM address, returning malicious-history flags, tiered risk scoring, and plain-language summaries via x402 payment.

Enables AI agents to inspect the public NFH protocol corpus, verify census status, and prepare bounded Ethereum wallet intents for claims and non-custodial market actions while never signing or submitting transactions.

Enables users to compare current Aerodrome veNFT voting positions, bounded claimable rewards, and selected pools' voting evidence on Base against a saved local baseline, with retryable, atomically stored change reports. All tools are read-only on chain, requiring no keys, signing, or transactions.