# invoices.org

> Document mailing gateway. Send physical mail via a single API call with x402 payment.

## API

- [Mail API Documentation](https://invoices.org/llms-full.txt): POST /api/mail — upload PDF, get quote, pay via x402, document is printed and mailed
- [API Specification](https://invoices.org/.well-known/openapi.json): OpenAPI 3.1 machine-readable spec
- [Agent Card](https://invoices.org/.well-known/agent-card.json): Google A2A agent discovery card

## About

invoices.org is a 402 gateway — it makes physical mail agent-accessible via a single paid HTTP request. No signup, no API keys, no billing relationship. Pay via x402 and go.

Send a PDF, a recipient address, and your return address. We print the document, put it in an envelope, and mail it via USPS. $3.00 per letter, max 5 pages.

## How It Works

1. POST to /api/mail with a base64-encoded PDF, recipient address (`to`), and return address (`from`)
2. Document is screened for prohibited content (threats, fraud, hate speech, political material)
3. Receive a 402 response with a transaction ID, price quote, and x402 payment requirements
4. Re-send with x402 payment header and the transaction ID
5. Document is printed, enveloped, and mailed. You receive a tracking reference.

## Constraints

- Maximum 5 pages per document
- PDF must be base64-encoded
- Both `to` and `from` addresses are required
- Optional `use_type`: "operational" (default) or "marketing"

## Content Policy

Approved: invoices, business letters, marketing material, personal correspondence, legal notices, contracts
Rejected: threats, harassment, hate speech, fraud/impersonation, political campaign material, disinformation

## Payment

This service uses the x402 protocol for payment. USDC on Base network. No accounts, no API keys, no signup. Payment is embedded in the HTTP request.

Learn more about x402: https://www.x402.org

## Policies

- [No Refunds Policy](https://invoices.org/policy/no-refunds): All payments are final once a document is submitted for mailing.

## Provider

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