> ## Documentation Index > Fetch the complete documentation index at: https://docs.closient.com/llms.txt > Use this file to discover all available pages before exploring further. # Generate a single 1D barcode > Render a 1D barcode for a GTIN. Symbology is auto-selected from GTIN length unless overridden via ``barcode_type``. Returns image bytes (``image/svg+xml``, ``image/png``, ``application/postscript``, or ``application/pdf``). **Caching**: responses are deterministic given the request body. The endpoint sets ``Cache-Control: public, max-age=2592000`` (30 days) and a strong ``ETag`` over the image bytes. Clients sending ``If-None-Match`` with a matching ETag get ``304 Not Modified``. ## OpenAPI ````yaml /openapi/openapi-products.json post /products/api/v1/barcode/ openapi: 3.1.0 info: title: Products API version: 1.0.0 description: > Look up, claim, and browse GTINs in the Closient product repository. ## Authentication All endpoints require an API key passed via the `X-API-Key` HTTP header, unless otherwise noted. ``` X-API-Key: csb__ ``` Generate API keys in **Settings > API Keys** in your dashboard, or via the Account API. Session-based (cookie) authentication is also accepted for browser-based access. ## Rate Limits | Tier | Requests / minute | Requests / day | |-------------|-------------------|----------------| | Default | 300 | 10,000 | | Custom | Contact us | Contact us | Rate-limit headers are included on every response so callers can self-throttle without hitting our 429s ("informed governor"): - `RateLimit-Policy` — every active window, e.g. `300;w=60, 10000;w=86400` - `RateLimit-Limit` — quota for the **most-restrictive** currently-active window - `RateLimit-Remaining` — requests left in that window - `RateLimit-Reset` — seconds until that window resets (relative; clock-skew safe) Legacy `X-RateLimit-*` aliases are also emitted for back-compat. `X-RateLimit-Reset` keeps the absolute Unix-timestamp shape to avoid breaking existing consumers. When rate-limited, you receive `429 Too Many Requests` with a `retry_after_seconds` field in the error envelope and a `Retry-After` header. ## Pagination List endpoints return paginated results in this envelope: ```json { "data": [...], "pagination": { "page": 1, "page_size": 25, "total_count": 342, "total_pages": 14, "has_next": true, "has_previous": false } } ``` Use `?page=2&page_size=50` query parameters. Maximum page size is 100. ## Error Responses All errors conform to [RFC 9457 Problem Details](https://www.rfc-editor.org/rfc/rfc9457) with `Content-Type: application/problem+json`: ```json { "type": "https://closient.com/docs/errors/not_found", "title": "Not Found", "status": 404, "detail": "The requested resource was not found.", "error_code": "not_found", "retryable": false, "timestamp": "2026-03-31T12:00:00+00:00" } ``` Common error codes: `unauthorized` (401), `forbidden` (403), `not_found` (404), `validation_error` (422), `rate_limited` (429), `internal_error` (500). termsOfService: https://www.closient.com/terms/ servers: - url: https://www.closient.com security: [] tags: - name: Products description: Look up, claim, and browse products and trade items. - name: Product Group description: Manage GDSN packaging hierarchy relationships. - name: Import description: Bulk import products from CSV files. - name: QR description: Generate QR codes encoding GS1 Digital Link URLs. - name: Codes description: Generate GS1 DataMatrix and 1D barcodes (EAN/UPC/ITF-14/Code128). - name: Digital Link description: >- Parse GS1 Digital Link URIs into structured AIs (GTIN, lot, expiry, serial). - name: Labels description: >- Bulk label-export jobs: ZIPs of QR / DataMatrix / 1D symbols and multi-up sheet PDFs, async via Celery with status polling. externalDocs: description: Closient Documentation url: https://docs.closient.com paths: /products/api/v1/barcode/: post: tags: - Codes summary: Generate a single 1D barcode description: >- Render a 1D barcode for a GTIN. Symbology is auto-selected from GTIN length unless overridden via ``barcode_type``. Returns image bytes (``image/svg+xml``, ``image/png``, ``application/postscript``, or ``application/pdf``). **Caching**: responses are deterministic given the request body. The endpoint sets ``Cache-Control: public, max-age=2592000`` (30 days) and a strong ``ETag`` over the image bytes. Clients sending ``If-None-Match`` with a matching ETag get ``304 Not Modified``. operationId: apps_products_api_codes_api_generate_barcode_1d parameters: [] requestBody: content: application/json: schema: $ref: '#/components/schemas/BarcodePayload' required: true responses: '200': description: OK content: application/json: schema: format: binary title: Response type: string '304': description: Not Modified '422': description: Unprocessable Content content: application/json: schema: $ref: '#/components/schemas/ErrorOut' security: - APIKeyHeaderAuth: [] - OAuthTokenAuth: [] - SessionAuth: [] components: schemas: BarcodePayload: description: Request body for synchronous 1D barcode generation. examples: - barcode_type: auto format: svg gtin: '00012345678905' - barcode_type: ean13 embed_font: true format: svg gtin: '00012345678905' module_height: 32 module_width: 0.5 quiet_zone: 10 write_text: true properties: gtin: description: GTIN (8/12/13/14 digits) or AI-bracketed string for GS1-128. title: Gtin type: string barcode_type: default: auto description: Symbology. ``auto`` picks the right family from GTIN length. enum: - auto - ean13 - ean8 - jan - upca - upce - itf14 - ean14 - code128 - gs1_128 - code39 title: Barcode Type type: string format: default: svg description: >- Output image format. ``svg`` is scalable vector output with embedded OCR-B HRT glyphs (the preferred print-shop format); ``png`` is raster output; ``eps`` is PostScript for legacy label-printer drivers; ``pdf`` (C-2852) is vector PDF for print houses — the SVG goes through svglib + reportlab so the PDF contains path operators, not a rasterised preview. enum: - svg - png - eps - pdf title: Format type: string module_width: default: 0.33 description: >- Module (narrowest bar) width in millimeters. Default 0.33mm matches GS1 retail-scan recommendations. Increase to ~0.5-1.0mm for outer-case ITF-14 / shipping containers. maximum: 2 minimum: 0.1 title: Module Width type: number module_height: default: 25 description: >- Symbol height in millimeters. Default 25.0mm matches GS1 retail minimum. Reduce for compact labels; increase for warehouse-scan distance. maximum: 100 minimum: 1 title: Module Height type: number font_size: default: 10 description: >- Human-readable text size in points. Default 10pt. Values below 8pt switch Zint to its compact-text rendering (``--small``); values 8pt and above render at standard size. maximum: 24 minimum: 4 title: Font Size type: number quiet_zone: default: 6.5 description: >- Quiet zone (white margin around the symbol) in millimeters. Default 6.5mm matches GS1 retail recommendations. Set to 0 to disable the quiet-zone markers entirely. maximum: 20 minimum: 0 title: Quiet Zone type: number write_text: default: true description: Render the human-readable GTIN below the bars. Default true. title: Write Text type: boolean embed_font: default: true description: >- Embed the OCR-B font in SVG output for portable rendering. Default true. No effect on PNG / EPS output. title: Embed Font type: boolean required: - gtin title: BarcodePayload type: object ErrorOut: description: |- RFC 9457 Problem Details response. All API errors are returned in this format with Content-Type: application/problem+json. examples: - detail: The requested resource was not found. error_code: not_found retryable: false status: 404 timestamp: '2026-03-31T12:00:00+00:00' title: Not Found type: https://closient.com/docs/errors/not_found - detail: Validation error. details: - loc: - body - name msg: Field required type: missing error_code: validation_error retryable: false status: 422 timestamp: '2026-03-31T12:00:00+00:00' title: Validation Error type: https://closient.com/docs/errors/validation_error - detail: Rate limit exceeded. Please try again later. error_code: rate_limited retry_after: 31 retryable: true status: 429 timestamp: '2026-03-31T12:00:00+00:00' title: Rate Limited type: https://closient.com/docs/errors/rate_limited properties: type: description: URI reference identifying the error type. title: Type type: string title: description: Short human-readable summary of the error. title: Title type: string status: description: HTTP status code. title: Status type: integer detail: description: Human-readable explanation of this specific occurrence. title: Detail type: string error_code: description: Machine-readable error code (e.g. not_found, unauthorized). title: Error Code type: string retryable: default: false description: Whether retrying the same request can succeed. title: Retryable type: boolean timestamp: description: ISO 8601 timestamp of when the error occurred. title: Timestamp type: string retry_after: anyOf: - type: integer - type: 'null' description: Seconds to wait before retrying (when applicable). title: Retry After owner_action_required: anyOf: - type: boolean - type: 'null' description: Whether the error requires account owner intervention. title: Owner Action Required details: description: Additional context (validation errors, etc.). title: Details required: - type - title - status - detail - error_code - timestamp title: ErrorOut type: object securitySchemes: APIKeyHeaderAuth: type: apiKey in: header name: X-API-Key OAuthTokenAuth: type: http scheme: bearer SessionAuth: type: apiKey in: cookie name: sessionid ````