> ## Documentation Index > Fetch the complete documentation index at: https://docs.paperjoy.co/llms.txt > Use this file to discover all available pages before exploring further. # Preview a postcard > Renders the handwritten side of a postcard as a PNG. Previews are free and never create an order. Requires the `postcards:write` ability. ## OpenAPI ````yaml /en/openapi.yaml post /api/postcards/preview openapi: 3.1.0 info: title: Paperjoy API version: '2026-10-19' description: >- Create, preview, and track real handwritten postcards. The API key decides whether a request runs in test or live mode. termsOfService: https://paperjoy.co/regulamin license: name: Proprietary url: https://paperjoy.co/regulamin servers: - url: https://paperjoy.co security: - bearerAuth: [] tags: - name: Account description: The authenticated account and its credit balance. - name: Postcards description: Create, preview, list, and retrieve postcards. - name: Signatures description: Custom handwritten signatures available to your organization. paths: /api/postcards/preview: post: tags: - Postcards summary: Preview a postcard description: >- Renders the handwritten side of a postcard as a PNG. Previews are free and never create an order. Requires the `postcards:write` ability. operationId: previewPostcard requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/PreviewPostcardRequest' example: content: |- Dear Anna, thank you for your first order! signature: Marta from the Linden Florist font_id: font-1 mistake: false responses: '200': description: A PNG image of the card. content: image/png: schema: type: string contentEncoding: binary '401': $ref: '#/components/responses/Unauthorized' '403': $ref: '#/components/responses/Forbidden' '422': $ref: '#/components/responses/ValidationError' '429': $ref: '#/components/responses/TooManyRequests' components: schemas: PreviewPostcardRequest: type: object required: - content - font_id properties: content: $ref: '#/components/schemas/Content' signature: $ref: '#/components/schemas/TypedSignature' signature_id: $ref: '#/components/schemas/SignatureIdInput' font_id: $ref: '#/components/schemas/FontId' mistake: $ref: '#/components/schemas/Mistake' Content: type: string maxLength: 300 description: >- The handwritten message. Line breaks (`\n`) and blank lines are kept. The text must fit on the card; see the `card_fit` validation error. TypedSignature: type: - string - 'null' maxLength: 50 description: >- A sign-off written on one line at the bottom of the card. Do not send together with `signature_id`. SignatureIdInput: type: - string - 'null' description: >- An active custom signature ID from `GET /api/signatures`. Requires a plan with custom signatures. Do not send together with `signature`. examples: - sig_ZeXOkSQjTp FontId: type: string enum: - font-1 - font-2 description: >- `font-1` is clear, rounded handwriting. `font-2` is a faster, joined-up cursive. Mistake: type: boolean default: false description: >- Cross out one word and write it again, like a real person would. The same message always gets the same correction. Error: type: object required: - message properties: message: type: string ValidationError: type: object required: - message - errors properties: message: type: string errors: type: object additionalProperties: type: array items: type: string responses: Unauthorized: description: The API key is missing, invalid, revoked, or expired. content: application/json: schema: $ref: '#/components/schemas/Error' example: message: Unauthenticated. Forbidden: description: >- The API key lacks the required ability, or the resource belongs to someone else. content: application/json: schema: $ref: '#/components/schemas/Error' example: message: This action is unauthorized. ValidationError: description: >- A field is invalid, the text does not fit on the card or envelope, or the `Idempotency-Key` is longer than 255 characters. content: application/json: schema: anyOf: - $ref: '#/components/schemas/ValidationError' - $ref: '#/components/schemas/Error' examples: field: summary: Invalid field value: message: The selected font id is invalid. errors: font_id: - The selected font id is invalid. card_fit: summary: Message does not fit on the card value: message: >- The content does not fit on the postcard. Shorten it or remove blank lines. errors: content: - >- The content does not fit on the postcard. Shorten it or remove blank lines. envelope_fit: summary: Address does not fit on the envelope value: message: The sender or recipient address does not fit on the envelope. errors: address: - >- The sender or recipient address does not fit on the envelope. draft_limit: summary: Too many open drafts value: message: >- You already have 100 open drafts. Submit or delete some of them before saving another draft. errors: draft: - >- You already have 100 open drafts. Submit or delete some of them before saving another draft. signature_unavailable: summary: Custom signature unavailable value: message: >- The selected signature is unavailable or is not active for your plan. errors: signature_id: - >- The selected signature is unavailable or is not active for your plan. TooManyRequests: description: A rate limit was exceeded. Wait before retrying. headers: Retry-After: description: Seconds to wait before retrying. schema: type: integer content: application/json: schema: $ref: '#/components/schemas/Error' example: message: Too Many Attempts. securitySchemes: bearerAuth: type: http scheme: bearer description: >- A Paperjoy API key. Keys starting with `pj_test_` use test mode; keys starting with `pj_live_` use live mode. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.