> ## Documentation Index > Fetch the complete documentation index at: https://docs.aropay.aro.media/llms.txt > Use this file to discover all available pages before exploring further. # Download letter PDF > The printable letter: a single US Letter page with sender and recipient blocks, the amount panel (sealed letters print `••••••• cAROUSD`), the QR encoding `claimUrl`, the claim code for manual entry, the expiry date and a one-time-claim warning. Available from `ESCROWED` onwards. `DRAFT` and `FAILED` letters return `409 letter_not_printable`. `CLAIMED`, `VOIDED` and `EXPIRED` letters render with a large `CLAIMED` / `VOID` / `EXPIRED` stamp across the page so a reprint cannot pass as live. ## OpenAPI ````yaml /api-reference/openapi.yaml get /transfer/letter/{id}/pdf openapi: 3.1.0 info: title: AroPay API version: 1.0.0 description: | The AroPay API for orchestrating sealed, private payments on public ledgers, built on the Aro Confidential Rails (Zama Protocol FHE). Two environments run the same API: Production on Ethereum Mainnet (`aropay.aro.media`, real funds) and the Sandbox on Sepolia (`dev.aropay.aro.media`, test funds and a faucet). Integrations built against the sandbox carry over unchanged; the faucet (`POST /fund`) is sandbox-only and returns 404 on production. Every response (except the flat Sandbox probes) uses the shared envelope: `{ "ok": true, "data": … }` on success and `{ "ok": false, "error": { "code", "message", "details?" } }` on failure. Amounts are decimal strings in human units (e.g. `"125.50"`). Write requests must send `Content-Type: application/json`. contact: name: Aro Media url: https://aro.media servers: - url: https://aropay.aro.media/api/v1 description: Production (Ethereum Mainnet) - url: https://dev.aropay.aro.media/api/v1 description: Sandbox (Sepolia) - url: http://aropay.localhost:3000/api/v1 description: Local development security: - apiKeyAuth: [] - sessionCookie: [] tags: - name: Auth description: Password, TOTP, and passkey login; session inspection and logout. - name: Profile & security description: Profile, password, two-factor authentication, and passkey management. x-group: Profile & security - name: API keys description: Programmatic credentials. Creation and revocation are session-only. - name: Wallets description: Custodial and external (watch-only) wallets. - name: Balances description: Balance triples and lightweight gas reads. - name: Money movement description: | Faucet funding, minting, transfers, and redemptions. All four are asynchronous: the request is validated and recorded, the response is `201` with the transaction in status `QUEUED` (`txHash: null`), and a background worker executes it. Poll `GET /transactions/{id}` until `status` is `CONFIRMED`, `SETTLED`, or `FAILED`. Execution failures surface as status `FAILED` with `errorCode` on the transaction, never as an HTTP error on the POST. - name: Aro Mail description: >- Letters of value: escrow cAROUSD, print or mail through Lob, and let the recipient claim by QR or code. - name: Transactions description: >- History, single-transaction reads (pure database reads), and notarized receipts. - name: Sandbox description: Unauthenticated status and echo probes with a flat response shape. paths: /transfer/letter/{id}/pdf: get: tags: - Aro Mail summary: Download letter PDF description: | The printable letter: a single US Letter page with sender and recipient blocks, the amount panel (sealed letters print `••••••• cAROUSD`), the QR encoding `claimUrl`, the claim code for manual entry, the expiry date and a one-time-claim warning. Available from `ESCROWED` onwards. `DRAFT` and `FAILED` letters return `409 letter_not_printable`. `CLAIMED`, `VOIDED` and `EXPIRED` letters render with a large `CLAIMED` / `VOID` / `EXPIRED` stamp across the page so a reprint cannot pass as live. operationId: getLetterPdf parameters: - $ref: '#/components/parameters/LetterId' responses: '200': description: The letter as a PDF. headers: Content-Disposition: description: '`inline; filename="aro-mail-.pdf"`' schema: type: string content: application/pdf: schema: type: string format: binary '401': $ref: '#/components/responses/Unauthorized' '403': $ref: '#/components/responses/AccountDisabled' '404': $ref: '#/components/responses/LetterNotFound' '409': description: >- The letter is `DRAFT` or `FAILED`; there is nothing escrowed to print. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: ok: false error: code: letter_not_printable message: The letter is not printable until its escrow is confirmed. '429': $ref: '#/components/responses/RateLimited' '500': $ref: '#/components/responses/InternalError' components: parameters: LetterId: name: id in: path required: true schema: type: string description: Letter ID. responses: Unauthorized: description: Missing or invalid credential. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: ok: false error: code: invalid_api_key message: Invalid API key. AccountDisabled: description: The account has been deactivated. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: ok: false error: code: account_disabled message: This account is disabled. LetterNotFound: description: >- No letter with this id in your account (or no letter matches the claim code). content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: ok: false error: code: letter_not_found message: Letter not found. RateLimited: description: Rate limit exceeded. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: ok: false error: code: rate_limited message: Too many requests. Try again shortly. InternalError: description: Unexpected server error. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: ok: false error: code: internal_error message: An unexpected error occurred. schemas: ErrorResponse: type: object description: The shared failure envelope. required: - ok - error properties: ok: const: false error: type: object required: - code - message properties: code: type: string description: Machine-readable error code; match on this, not `message`. message: type: string details: description: Structured context, e.g. per-field validation issues. securitySchemes: apiKeyAuth: type: http scheme: bearer bearerFormat: aro_sk_… description: | AroPay API key, sent as `Authorization: Bearer aro_sk_…`. Created in the dashboard under Settings → API keys. Takes precedence over a session cookie when both are present. x-default: aro_sk_your_key_here sessionCookie: type: apiKey in: cookie name: aropay_session description: | Browser session cookie minted by `POST /auth/login` (or passkey login). httpOnly, `SameSite=Lax`, 24 h TTL. Endpoints marked **Session-only** accept only this credential and return `403 session_required` for API keys. ````