moltpost
Send real physical postcards anywhere in the world. Pay with x402 (USDC on Base), Stripe, or manual USDC transfer. No signup, no API key — just one API call.
Install via CLI (Recommended)
clawhub install openclaw/skills/skills/cktc/moltpostMoltpost
Send real physical postcards anywhere in the world through a single API call. No registration. No API key. No account. Just compose, pay, and a printed postcard arrives in the mail.
Base URL: https://api.moltpost.io/v1
Skill Files
| File | URL |
|---|---|
| SKILL.md (this file) | https://moltpost.io/skill.md |
| HEARTBEAT.md | https://moltpost.io/heartbeat.md |
How It Works
Moltpost supports three payment methods:
- x402 (preferred for agents with crypto wallets) — one-step, gasless USDC payment via HTTP headers
- Stripe (fallback for humans) — credit card payment via Stripe checkout link
- Manual USDC (legacy) — two-step onchain transfer + confirmation
x402 — Preferred for Agents (Recommended)
The x402 protocol lets agents pay with USDC directly via HTTP — no gas fees, no wallet management, no two-step flow. If your agent has a crypto wallet, always use x402.
- Agent calls
POST /v1/postcards/x402with recipient address and content (no payment header) - API returns HTTP 402 with payment requirements (amount, recipient, network)
- Agent signs an EIP-712 authorization (gasless — no ETH needed)
- Agent retries the same request with
X-PAYMENT(v1) orPAYMENT-SIGNATURE(v2) header containing the signed payload - Moltpost verifies and settles the payment via the x402 facilitator, creates the postcard, and returns HTTP 201 with postcard details
No gas fees. No separate confirmation step. One round-trip after signing.
Base Sepolia (testnet) payments use mock fulfillment — the postcard is marked "sent" but not printed. Use Base mainnet for real postcards.
Stripe (fallback for humans)
- Agent calls
POST /v1/postcardswith recipient address and content - API returns a Stripe payment link and a postcard ID
- Human owner clicks the payment link and pays (agent must present this link)
- Moltpost prints and mails the physical postcard
The human must approve and pay. Never attempt to complete payment on behalf of the owner. Always present the payment link and let them decide.
Manual USDC (legacy)
- Agent calls
POST /v1/postcardswith"payment_method": "usdc"and"usdc_chain": "base-sepolia"(or"base"for mainnet) - API returns a
usdc_paymentobject with the recipient wallet, exact USDC amount, token contract, and deadline - Human (or agent with wallet access) sends the exact USDC amount to the recipient wallet onchain
- Agent calls
POST /v1/postcards/{id}/confirm-paymentwith the transaction hash - Moltpost verifies the transfer onchain and fulfills the postcard
Note: Base Sepolia (testnet) payments use mock fulfillment — the postcard is marked as "sent" but not actually printed. Use "base" for real postcards on mainnet.
Agent decision guide: If you have a crypto wallet → use x402. If you don't → use Stripe and present the payment link to your owner.
Important: Agent Guidelines
Metadata
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Find the right skillPaste this into your clawhub.json to enable this plugin.
{
"plugins": {
"official-cktc-moltpost": {
"enabled": true,
"auto_update": true
}
}
}