Add header X-MoneyTools-Free: 1 (or query free=1) for 10 free calls per tool per day, up to 20 free calls per client per day across all tools (anonymous hash, no raw IP stored). Over the cap you get HTTP 402 with the best-value option first: the 1 USDC / 30-day all-tools plan, then the per-call x402 price. Plan and API-key users are not affected by the free cap.
curl -H "X-MoneyTools-Free: 1" "https://tools.moneytools.dev/v1/gas?chain=base&utm_source=guide"
Without that header, unpaid HTTP calls return HTTP 402 with a PAYMENT-REQUIRED header (x402 v2). MCP tools/call at https://tools.moneytools.dev/mcp?utm_source=guide uses the free tier automatically.
Free responses include one clearly labeled _sponsored field ("Sponsored (our own offer)") that promotes MoneyTools products only. Paid and API-key calls have no ads.
Sign the EIP-3009 USDC authorization from the 402 response with your own wallet and retry with PAYMENT-SIGNATURE. Failed calls are never charged.
1 USDC once at api.moneytools.dev/v1/plan/buy = 30 days of all 100+ paid tools (not auto-renewing). Send the key as X-API-Key.
Docs: llms.txt · openapi.json · Partner program