Free tools for humans. Paid APIs for AI agents.

Every AgentTools tool — calculators, converters, niche databases — is a free web page and, at the same URL family, a machine-native JSON API that AI agents pay for per call with the x402 protocol (USDC on Base).

Integrate with your agent →/llms.txt OpenAPI spec

Browse by category

🧮Calculators

11 tools

Free online calculators for everyday math, finance and health — each one also available as a machine-readable paid API for AI agents.

🔁Converters

9 tools

Unit, currency, encoding and data-format converters. Instant answers for humans; deterministic JSON APIs for agents.

🗄️Databases

1 tools

Curated niche databases — countries, currencies, timezones, holidays and more. Browseable for humans, queryable via API for agents.

🌍 Countries Database

📡Live Data

9 tools

Real-time data agents cannot fake: current time, exchange rates, crypto prices, weather, holidays, IP and DNS lookups. Free public sources, cached, no API keys.

🛠️Dev Tools

16 tools

Developer utilities: encoders, decoders, parsers, formatters and reference databases like HTTP status codes and MIME types.

⛓️Crypto & Web3

4 tools

Gas calculators, unit converters, staking math and chain reference data for the web3 ecosystem.

📈Finance & Business

4 tools

Mortgage, interest, ROI and payroll calculators plus IBAN/VAT validation and financial reference data.

How agent payments work

1 · Agent calls the tool's /api/v1/… endpoint
2 · Server answers 402 with payment requirements
3 · Agent pays USDC via its x402 client (no account, no key)
4 · Same request returns 200 with the result

Free tools for humans, machine-native APIs for AI agents. Prices: $0.001–$0.005 per call. Full integration guide.