SendInkwire for agents

A careful path from structured data to physical mail.

SendInkwire exposes a machine-payable API for rendering, pricing, paying for, and tracking one card or a personalized campaign. Live submission controls protect every irreversible handoff to physical fulfillment.

THE SAFETY RULE

Network calls can be retried. Physical mail cannot be recalled. Exact content approval, idempotency, durable state, and manual review protect that boundary.

Agent flow

A protocol, not another checkout page.

The API returns rendered messages, complete normalized recipient addresses, validation findings, price, an approval hash, an MPP payment challenge, a private status token, and recipient-level state.

Discover

Read /llms.txt or /openapi.json. No account or browser session is required for discovery.

Quote and render

Submit one card or up to 100 recipients. Inspect each final message, warning, error, and the exact campaign price.

Approve

Return the approval hash for the reviewed content. Any content change creates a mismatch and blocks the send.

Preflight, then pay

Call campaign preflight immediately before payment and stop before payment when preflight reports ready=false. Only an approved campaign may continue to its HTTP 402 challenge.

Track privately

Use the opaque campaign token to retrieve recipient-level status without exposing mailing addresses.

The first request

Discoverable by software. Readable by people.

// Render, normalize, and price every card before payment
const quote = await fetch(
  'https://api.sendinkwire.com/v1/campaign-quotes',
  {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({
      messageTemplate: 'Thank you, {{firstName}}. Your support mattered.',
      recipients: [/* personalized recipients */]
    })
  }
)

// Show every message, complete address, price, and approvalHash.
// Create the campaign, require ready=true, then request payment.

MPP in plain English

Machine Payments Protocol lets an API respond with HTTP 402 and a structured payment requirement. An authorized agent can satisfy that requirement and retry the request. In SendInkwire, payment happens only after content, the complete address, the quote, and campaign readiness have been reviewed.

What developers get

API

OpenAPI + llms.txt

Human-readable discovery plus a structured contract for tools and agents.

SAFE

Immutable approval

A content fingerprint binds the reviewed message to the paid send.

ONCE

Idempotent intent

Repeat the same request without creating another logical physical action.

STATE

Private tracking

Follow every recipient with a private token and an address-free status response.

Production API

Explore the contract before crossing the payment boundary.

Quotes, campaign creation, and preflight are unpaid. Do not satisfy a payment challenge unless the user approved the exact content, address, and total and preflight still reports ready=true.

Read llms.txt Open API schema