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Sendpaper prints and mails real postcards and letters to US addresses via USPS First-Class. It is built to be called by AI agents (Codex, Muse Code, Claude, ChatGPT or any MCP client), and it works just as well from a plain REST call or the website.

Quickstart

Connect an agent and send your first postcard in two minutes.

MCP tools

The five tools your agent gets, and what each returns.

API reference

Create postcards and letters with one HTTP request.

How an order works

Payment, human review, printing and mailing.

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Why it is safe to give an agent

  • No API key, no stored card. Every order comes back with a checkout_url. A person pays it in Stripe Checkout. An agent can draft mail all day but can never spend money on its own.
  • What you see is what prints. Each order has a preview_url that renders the exact print sheet.
  • A person reviews every piece before it is printed. Threatening, harassing, fraudulent or obscene mail is refused and refunded.
  • Retries are safe. Pass an idempotency key and a retried call returns the original order, never a duplicate.

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Prices

Prices include printing, envelope and First-Class postage. US addresses only.