"Services or tools that don't require a separate 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.

Real-time crypto, stock, and prediction-market data for agents — prices, indicators, funding rates, DeFi TVL, macro calendar, and an AI momentum score. Configure one Base wallet key and it just works. No signup, no dashboard, no 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 AI agents to access 13 paid micro-tools over x402, paying per request in USDC on Base without API keys or signup. It covers email deliverability, grading, and templates, plus utilities like crypto prices, domain age, hashing, JSON conversion, JWT decoding, regex, slugs, UUIDs, and weather.

An unofficial, read-only MCP server for Sarwa Odyssey that provides portfolio, holdings, transactions, watchlists, and agent snapshots via deterministic JSON documents.

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.

Provides access to measured x402 ecosystem data, allowing users to query which merchants actually accept payment (verified by real on-chain settlements) and explore market concentration and health statistics.

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 querying cryptocurrency portfolio data, transaction history, net worth, and historical snapshots across 20+ blockchains via the Octav API.

Pay-per-call tools for AI agents including trust checks, due diligence, market data, and human-verified approvals, settled in USDC on Base via the x402 protocol.

Enables interactive access to TradeSearcher strategies and backtests via CLI and MCP, allowing agents to search, backtest, and compare trading strategies.

A collection of three zero-dependency MCP servers for web scraping via Chrome DevTools Protocol, crypto wallet and price monitoring, and email validation with SMTP sending.

Provides 63 production-ready API tools for AI agents, including web scraping, AI generation, crypto data, OCR, image generation, audio transcription, text-to-speech, email, and domain lookup.

Enables MCP clients to access exchange rates for 160+ currencies, currency conversion, historical rates, time series, crypto, metal and stock prices, usage checks, and rate alerts.

Enables AI agents to fetch real-time trading signals and technical indicators for cryptocurrencies using Binance market data.

pay-per-call x402 API endpoints as MCP tools — web search, page-to-markdown, PDF extract, JSON repair/validate, crypto price, weather, IP geo, DNS, markdown lint + 20 agent-commerce aliases. Each tool proxies to vibes-coded.com and settles via x402 (USDC/Solana). Free-trial endpoints need no auth; paid ones need an x402 signature. Catalog is fetched live, so new endpoints appear automatically.

Enables AI agents to explain DigiDollar transactions recorded on DigiByte, including mints, transfers, redemptions, amounts in cents, lock tiers, burns, and collateral releases, using bundled fixtures or an optional live explorer.