> ## Documentation Index > Fetch the complete documentation index at: https://docs.vidgo.ai/llms.txt > Use this file to discover all available pages before exploring further. # FLUX 3 Klein Text to Image > The FLUX 3 Klein Text to Image API generates 1–4 images from a prompt at 1K, 2K or 4K, with 7 aspect ratios or custom sizes and PNG, JPEG or WebP output. > [!TIP] > > 1. After submission, a `task_id` will be returned. If you provided a `callback_url`, when the task status becomes `finished` or `failed`, a POST request will be sent to the `callback_url`. > 2. Regardless of whether `callback_url` is provided, you can retrieve the result through the unified [Query Task Status](https://docs.vidgo.ai/api-manual/task-management/status.md) endpoint. FLUX 3 Klein Text to Image creates images from a prompt at 1K, 2K or 4K, using seven aspect-ratio presets or an exact custom size. It suits product shots, marketing visuals, concept art and high-volume image pipelines where fast turnaround matters. FLUX 3 Klein is the compact member of Black Forest Labs' FLUX 3 image family, built for fast generation and instruction-based editing. Vidgo exposes it as two model IDs: [Text to Image](https://docs.vidgo.ai/api-manual/image-series/blackforestlabs-flux-3-klein-text-to-image.md) and [Edit](https://docs.vidgo.ai/api-manual/image-series/blackforestlabs-flux-3-klein-edit.md). ## Models * **blackforestlabs/flux-3-klein/text-to-image** — Text-to-image with FLUX 3 Klein, 1–4 images at 1K, 2K or 4K. ## Features * Text-to-image from a single prompt. * Three resolution tiers: `1K`, `2K`, `4K`. * Seven aspect-ratio presets, or a custom `WIDTHxHEIGHT` from 256 to 4096 px per side. * PNG, JPEG or WebP output, 1–4 images per request. ## Required parameters * `prompt` (string): The image you want. Must not be blank. ## Optional parameters * `n` (integer): Number of images, `1`–`4`. Default `1`. * `resolution` (string): `1K`, `2K` or `4K`. Default `1K`. See [Resolution](#resolution). * `size` (string): Preset or custom `WIDTHxHEIGHT`. Default `1:1`. See [Resolution](#resolution). * `output_format` (string): `png`, `jpeg` or `webp`. Default `png`. * `enable_safety_checker` (boolean): Upstream safety checker. Default `true`. ## Resolution * With a preset `size` (`1:1`, `4:3`, `3:4`, `16:9`, `9:16`, `3:2`, `2:3`), the image is scaled so its long edge matches the tier: `1K` → 1024 px, `2K` → 2048 px, `4K` → 4096 px. * With a custom `size` such as `1920x1080`, each side must be 256–4096 and a multiple of 16, and you must send `resolution` matching the long edge: up to 1024 → `1K`, up to 2048 → `2K`, above 2048 → `4K`. A mismatch returns 400. | `resolution` | Long edge (presets) | Custom long edge | | - | - | - | | `1K` | 1024 px | ≤ 1024 px | | `2K` | 2048 px | 1025–2048 px | | `4K` | 4096 px | 2049–4096 px | ## Output The finished task returns one file per requested image (`n`) in the `files` array of [Query Task Status](https://docs.vidgo.ai/api-manual/task-management/status.md) and the callback payload. ## Examples * **1K square image**: a product photo at `1:1`, `1K`, PNG. * **Custom 4K size, two JPEGs, with callback**: `size: 3840x2160` with `resolution: 4K` (long edge above 2048), `n: 2`, JPEG, with a `callback_url`. ## Notes * This ID takes text only; `image_urls` returns 400. To edit or combine images, use [FLUX 3 Klein Edit](https://docs.vidgo.ai/api-manual/image-series/blackforestlabs-flux-3-klein-edit.md). * Fields not listed above return 400. `model` and `callback_url` belong at the request root, not inside `input`. * Credits are reserved at submission and depend on `resolution` and `n`. Text-to-image and edit use the same rates. A failed task is refunded in full. See the [pricing page](https://vidgo.ai/apis/api-pricing) for current rates. ## OpenAPI ````yaml api-manual/image-series/blackforestlabs-flux-3-klein-text-to-image.json POST /api/generate/submit openapi: 3.0.0 info: title: Vidgo API - FLUX 3 Klein Text to Image description: >- The FLUX 3 Klein Text to Image API generates 1–4 images from a prompt at 1K, 2K or 4K, with 7 aspect ratios or custom sizes and PNG, JPEG or WebP output. version: 1.0.0 servers: - url: https://api.vidgo.ai description: Production server security: - BearerAuth: [] paths: /api/generate/submit: post: tags: - Image Series summary: FLUX 3 Klein Text to Image description: >- Send only the `input` fields listed for this model. Any other field, including `image_urls`, returns 400. A custom `WIDTHxHEIGHT` size needs a `resolution` that matches its long edge. operationId: submit_blackforestlabs_flux_3_klein_text_to_image requestBody: required: true content: application/json: schema: type: object required: - model - input properties: model: type: string description: Model ID. Use `blackforestlabs/flux-3-klein/text-to-image`. example: blackforestlabs/flux-3-klein/text-to-image callback_url: type: string format: uri nullable: true description: >- Optional public HTTP(S) endpoint that receives a POST when the task becomes `finished` or `failed`. HTTPS is recommended. Omit it, or send `null` or an empty string, to disable callbacks. example: https://your-domain.com/callback input: type: object required: - prompt properties: prompt: type: string minLength: 1 example: >- Studio product photo of a matte black water bottle on wet slate, soft rim light description: Text prompt describing the image. Must not be blank. 'n': type: integer minimum: 1 maximum: 4 default: 1 description: Number of images to generate. resolution: type: string enum: - 1K - 2K - 4K default: 1K description: >- Resolution tier (case-insensitive). Presets are scaled so the long edge is 1024, 2048 or 4096 px. It sets the billing rate. With a custom `size`, send the tier that matches its long edge. size: type: string default: '1:1' example: '16:9' description: >- Aspect-ratio preset (`1:1`, `4:3`, `3:4`, `16:9`, `9:16`, `3:2`, `2:3`) or a custom `WIDTHxHEIGHT` with each side 256–4096 and a multiple of 16. A custom size needs an explicit `resolution` matching its long edge: up to 1024 → `1K`, up to 2048 → `2K`, otherwise `4K`. output_format: type: string enum: - png - jpeg - webp default: png description: Image file format. enable_safety_checker: type: boolean default: true description: Run the upstream safety checker. additionalProperties: false description: Generation parameters. examples: preset: summary: 1K square image value: model: blackforestlabs/flux-3-klein/text-to-image input: prompt: >- Studio product photo of a matte black water bottle on wet slate, soft rim light 'n': 1 resolution: 1K size: '1:1' output_format: png custom_4k: summary: Custom 4K size, two JPEGs, with callback value: model: blackforestlabs/flux-3-klein/text-to-image callback_url: https://your-domain.com/callback input: prompt: >- Aerial view of terraced rice fields at golden hour, mist in the valleys, ultra detailed 'n': 2 resolution: 4K size: 3840x2160 output_format: jpeg enable_safety_checker: true responses: '200': description: Task submitted content: application/json: schema: type: object required: - code - data properties: code: type: integer enum: - 200 description: HTTP status code. data: type: object required: - task_id - status - created_time properties: task_id: type: string description: >- Task ID. Use it with [Query Task Status](/api-manual/task-management/status). status: type: string enum: - not_started description: Initial task status. created_time: type: string format: date-time description: Time the task was created (ISO 8601). example: code: 200 data: task_id: task-unified-1762160000-abc123 status: not_started created_time: '2026-11-03T10:30:00' '400': description: >- Invalid input, unsupported field, inaccessible media, or insufficient credits content: application/json: schema: type: object required: - detail properties: detail: oneOf: - type: string - type: object additionalProperties: true - type: array items: {} description: Error message. '401': description: Invalid credentials content: application/json: schema: type: object required: - detail properties: detail: oneOf: - type: string - type: object additionalProperties: true - type: array items: {} description: Error message. '403': description: Access denied content: application/json: schema: type: object required: - detail properties: detail: oneOf: - type: string - type: object additionalProperties: true - type: array items: {} description: Error message. '404': description: Unknown or disabled model content: application/json: schema: type: object required: - detail properties: detail: oneOf: - type: string - type: object additionalProperties: true - type: array items: {} description: Error message. '408': description: Request timed out content: text/plain: schema: type: string example: Request timeout '422': description: Invalid JSON or non-object request body content: application/json: schema: type: object required: - detail properties: detail: oneOf: - type: string - type: object additionalProperties: true - type: array items: {} description: Error message. '429': description: Rate or API key credit limit exceeded content: application/json: schema: type: object required: - detail properties: detail: oneOf: - type: string - type: object additionalProperties: true - type: array items: {} description: Error message. '500': description: Internal error content: application/json: schema: type: object required: - detail properties: detail: oneOf: - type: string - type: object additionalProperties: true - type: array items: {} description: Error message. '502': description: Unable to create the upstream generation task content: application/json: schema: type: object required: - detail properties: detail: oneOf: - type: string - type: object additionalProperties: true - type: array items: {} description: Error message. '503': description: The requested model is temporarily unavailable content: application/json: schema: type: object required: - detail properties: detail: oneOf: - type: string - type: object additionalProperties: true - type: array items: {} description: Error message. components: securitySchemes: BearerAuth: type: http scheme: bearer bearerFormat: API Key description: >- All API endpoints require Bearer Token authentication Get your API Key: Go to **Dashboard → API Key** ([API Key Management Page](https://vidgo.ai/apis/dashboard/api-key)) to get your API Key Add it to the request header: ``` Authorization: Bearer VIDGO_API_KEY ``` ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.