x402engine

Call 63 paid APIs via x402 micropayments. Each API call costs between $0.001 and $0.60, paid with USDC on Base/Solana or USDm on MegaETH.

What this skill does

This skill signs and submits stablecoin micropayments to call remote APIs on the user's behalf. It uses the EVM_PRIVATE_KEY environment variable to sign on-chain payment transactions. Each call deducts a small amount from the wallet.

Cost transparency: When presenting results, include the cost of the call (e.g. "Bitcoin is $97,500 (cost: $0.001)"). If the user asks about spending, show full budget breakdown.

Triggers

• "what's the price of bitcoin"
• "ethereum price"
• "show me trending crypto"
• "generate an image of a sunset"
• "run this python code"
• "transcribe this audio"
• "wallet activity of vitalik.eth"
• "ask gpt to explain x402"
• "scrape this url"
• "pin this to ipfs"
• "resolve vitalik.eth"
• "flights from JFK to LAX"
• "search hotels in Paris"
• "find cheap flights to Tokyo"
• "how much budget is left"
• "list available services"

How it works

1. Fetch cached service catalog from discovery endpoint (default: https://x402engine.app/.well-known/x402.json).
2. Score query against 63 service descriptions to find best match.
3. Run policy preflight — check per-tx caps, daily caps, and recipient allowlist before signing.
4. Call service via @x402/fetch — handles 402 payment flow automatically.
5. Return structured data to the agent for natural-language presentation.

Rules

• Present results naturally. Include the cost of each call so the user knows what was spent.
• If a payment fails due to insufficient funds, tell the user: "I need funds to access this service. Add USDC to your wallet to continue."
• If no matching service is found, say so plainly — don't expose internal routing details.
• Policy limits are authoritative — do not bypass spend caps or recipient allowlists.
• Keep all decisions explainable with reason codes internally.

Security

Required credential

• EVM_PRIVATE_KEY (required) — signs payment transactions. Use a dedicated wallet with limited funds — never your primary wallet. If not set, an ephemeral key is generated (no real funds, no payments possible).