The Postal Company API

The Postal Company API lets you send physical letters anywhere in the world from your application. Write your letter content, provide a recipient address, and we handle printing, enveloping, and postal delivery.

Quick start

Create an account

Top up your balance

Go to the Balance page and purchase credits. Each letter costs €2.50.

Create an API key

Go to API Keys and create a new key. Copy it — it’s only shown once.

Send a letter

curl -X POST https://thepostalcompany.com/api/v1/letters \
  -H "Authorization: Bearer tpc_your_api_key" \
  -H "Content-Type: application/json" \
  -d '{
    "recipient": "Jane Doe",
    "address": {
      "street": "Keizersgracht",
      "number": "123",
      "postalcode": "1015 CJ",
      "city": "Amsterdam",
      "country": "NL"
    },
    "content": "Dear Jane,\n\nThis is a test letter sent via the API.\n\nBest regards"
  }'

Key concepts

Credits — Pre-paid balance used to send letters. Each letter costs €2.50 via checkout or €2.25 via API.
API keys — Long-lived keys for authenticating API requests. You can create multiple keys and revoke them at any time.
Letters — Create letters as drafts to review them first, or send immediately. Once sent, letters are queued for printing and postal delivery.
Drafts — Letters created with send: false are saved as drafts. You can update them with PATCH and send them when ready with POST /api/v1/letters/:id/send.

AI agent skill

If you’re using an AI coding agent (like Claude Code, Cursor, or Copilot), you can download our agent skill file to give your agent full knowledge of the API. Add it to your project or paste it into your agent’s context.

Getting Started

Guides

Introduction

The Postal Company API

Quick start

Key concepts

AI agent skill

​The Postal Company API

​Quick start

​Key concepts

​AI agent skill

The Postal Company API

Quick start

Key concepts

AI agent skill