HTML/CSS to Image Generation API

openapi: 3.0.1
info:
  title: HTML/CSS to Image API
  description: >-
    REST API for rendering HTML, CSS, and JavaScript (or a URL) into high
    quality images (PNG, JPG, WebP, PDF). Supports single and batch image
    creation, image retrieval with resize/crop options, reusable templates
    with variable substitution, and HMAC-signed URLs for GET-based templated
    image generation. Authentication is HTTP Basic using your User ID as the
    username and your API Key as the password.
  termsOfService: https://htmlcsstoimage.com/terms
  contact:
    name: HTML/CSS to Image Support
    email: support@htmlcsstoimage.com
    url: https://htmlcsstoimage.com
  version: '1.0'
servers:
  - url: https://hcti.io/v1
security:
  - basicAuth: []
paths:
  /image:
    post:
      operationId: createImage
      tags:
        - Image Generation
      summary: Create an image from HTML/CSS or a URL.
      description: >-
        Render HTML, CSS, and JavaScript into an image and return its ID and a
        permanent hosted URL. Provide either `html` or `url` (not both).
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreateImageRequest'
      responses:
        '200':
          description: The created image, with its ID and permanent URL.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Image'
        '401':
          description: Missing or invalid authentication.
        '422':
          description: Validation error (e.g. neither or both of html and url provided).
  /image/batch:
    post:
      operationId: createImageBatch
      tags:
        - Image Generation
      summary: Create multiple images in a single request.
      description: >-
        Render up to 25 image variations in one request. Shared options are
        provided in `default_options` and merged into each `variations` entry.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreateImageBatchRequest'
      responses:
        '200':
          description: The created images.
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/Image'
        '401':
          description: Missing or invalid authentication.
    delete:
      operationId: deleteImageBatch
      tags:
        - Image Generation
      summary: Delete multiple images in a single request.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              required:
                - ids
              properties:
                ids:
                  type: array
                  items:
                    type: string
                  description: Array of image IDs to delete.
      responses:
        '202':
          description: Accepted; the images will be deleted.
        '401':
          description: Missing or invalid authentication.
  /image/{image_id}:
    get:
      operationId: getImage
      tags:
        - Image Generation
      summary: Retrieve a rendered image.
      description: >-
        Fetch a previously created image. Append a format extension (.png,
        .jpg, .webp, .pdf) to control the output format; PNG is the default.
        Query parameters allow on-the-fly resize and crop.
      parameters:
        - name: image_id
          in: path
          required: true
          schema:
            type: string
        - name: width
          in: query
          schema:
            type: integer
          description: Resize width in pixels.
        - name: height
          in: query
          schema:
            type: integer
          description: Resize height in pixels.
        - name: dpi
          in: query
          schema:
            type: integer
          description: Output DPI.
        - name: aspect_ratio
          in: query
          schema:
            type: string
          description: Aspect ratio to apply, e.g. "16:9".
        - name: crop_width
          in: query
          schema:
            type: integer
        - name: crop_height
          in: query
          schema:
            type: integer
        - name: dl
          in: query
          schema:
            type: integer
          description: Set to 1 to force a download response.
      responses:
        '200':
          description: The rendered image binary.
          content:
            image/png:
              schema:
                type: string
                format: binary
            image/jpeg:
              schema:
                type: string
                format: binary
            image/webp:
              schema:
                type: string
                format: binary
            application/pdf:
              schema:
                type: string
                format: binary
        '404':
          description: Image not found.
    delete:
      operationId: deleteImage
      tags:
        - Image Generation
      summary: Delete an image.
      parameters:
        - name: image_id
          in: path
          required: true
          schema:
            type: string
      responses:
        '202':
          description: Accepted; the image will be deleted.
        '401':
          description: Missing or invalid authentication.
  /images:
    get:
      operationId: listImages
      tags:
        - Image Generation
      summary: List images.
      description: Return a paginated list of images created on the account.
      parameters:
        - name: count
          in: query
          schema:
            type: integer
            maximum: 50
          description: Number of images to return (max 50).
        - name: page_token
          in: query
          schema:
            type: string
          description: Pagination token returned by a previous call.
      responses:
        '200':
          description: A paginated list of images.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ImageList'
        '401':
          description: Missing or invalid authentication.
  /usage:
    get:
      operationId: getUsage
      tags:
        - Image Generation
      summary: Check account usage.
      description: >-
        Return hourly, daily, and monthly image usage statistics plus billing
        period totals for the account.
      responses:
        '200':
          description: Account usage statistics.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Usage'
        '401':
          description: Missing or invalid authentication.
  /template:
    get:
      operationId: listTemplates
      tags:
        - Templates
      summary: List all templates.
      responses:
        '200':
          description: The account's templates.
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/Template'
        '401':
          description: Missing or invalid authentication.
    post:
      operationId: createTemplate
      tags:
        - Templates
      summary: Create a template.
      description: >-
        Create a reusable HTML/CSS template containing named variables that are
        substituted at render time via template_values.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreateTemplateRequest'
      responses:
        '200':
          description: The created template.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Template'
        '401':
          description: Missing or invalid authentication.
  /template/{template_id}:
    get:
      operationId: listTemplateVersions
      tags:
        - Templates
      summary: List versions of a template.
      parameters:
        - name: template_id
          in: path
          required: true
          schema:
            type: string
      responses:
        '200':
          description: The versions of the template.
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/Template'
        '404':
          description: Template not found.
    post:
      operationId: editTemplate
      tags:
        - Templates
      summary: Edit a template.
      description: Create a new version of an existing template.
      parameters:
        - name: template_id
          in: path
          required: true
          schema:
            type: string
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreateTemplateRequest'
      responses:
        '200':
          description: The updated template.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Template'
        '401':
          description: Missing or invalid authentication.
  /image/{template_id}:
    post:
      operationId: createTemplatedImage
      tags:
        - Templates
      summary: Generate an image from a template.
      description: >-
        Render a template into an image by supplying template_values for its
        named variables. Accepts JSON or form data; with form data the
        template_values must be JSON encoded.
      parameters:
        - name: template_id
          in: path
          required: true
          schema:
            type: string
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreateTemplatedImageRequest'
      responses:
        '200':
          description: The created image.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Image'
        '401':
          description: Missing or invalid authentication.
  /image/{template_id}/{template_version}:
    post:
      operationId: createTemplatedImageVersion
      tags:
        - Templates
      summary: Generate an image from a specific template version.
      parameters:
        - name: template_id
          in: path
          required: true
          schema:
            type: string
        - name: template_version
          in: path
          required: true
          schema:
            type: string
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreateTemplatedImageRequest'
      responses:
        '200':
          description: The created image.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Image'
        '401':
          description: Missing or invalid authentication.
  /image/{template_id}/{signed_token}{format}:
    get:
      operationId: getSignedTemplatedImage
      tags:
        - Signed URLs
      summary: Generate a templated image from an HMAC-signed URL.
      description: >-
        Render an image from a template using a signed token that encodes the
        template_values. The token is HMAC-signed with the API key so values
        cannot be modified by anyone without the key, allowing image generation
        from a simple GET request with no POST or stored URL.
      security: []
      parameters:
        - name: template_id
          in: path
          required: true
          schema:
            type: string
        - name: signed_token
          in: path
          required: true
          schema:
            type: string
          description: HMAC-signed token encoding the template_values.
        - name: format
          in: path
          required: true
          schema:
            type: string
            enum:
              - .png
              - .jpg
              - .webp
              - .pdf
          description: Output format extension.
      responses:
        '200':
          description: The rendered image binary.
          content:
            image/png:
              schema:
                type: string
                format: binary
            image/jpeg:
              schema:
                type: string
                format: binary
            image/webp:
              schema:
                type: string
                format: binary
            application/pdf:
              schema:
                type: string
                format: binary
        '403':
          description: Invalid signature.
components:
  securitySchemes:
    basicAuth:
      type: http
      scheme: basic
      description: >-
        HTTP Basic authentication using your User ID as the username and your
        API Key as the password, both from the HTML/CSS to Image dashboard.
  schemas:
    CreateImageRequest:
      type: object
      description: One of `html` or `url` is required (not both).
      properties:
        html:
          type: string
          description: The HTML markup to render.
        url:
          type: string
          description: A URL to render instead of inline HTML.
        css:
          type: string
          description: CSS to apply to the HTML.
        google_fonts:
          type: string
          description: Comma-separated Google Fonts to load, e.g. "Roboto".
        selector:
          type: string
          description: CSS selector of the element to capture.
        ms_delay:
          type: integer
          description: Milliseconds to wait before capturing.
        max_wait_ms:
          type: integer
          description: Maximum milliseconds to wait for the page.
        device_scale:
          type: number
          description: Device scale factor for higher resolution output.
        render_when_ready:
          type: boolean
          description: Wait for a window.renderWhenReady() signal before capturing.
        full_screen:
          type: boolean
          description: Capture the full screen rather than the content size.
        block_consent_banners:
          type: boolean
          description: Attempt to hide cookie/consent banners.
        viewport_width:
          type: integer
        viewport_height:
          type: integer
        viewport_mobile:
          type: boolean
        viewport_landscape:
          type: boolean
        viewport_touch:
          type: boolean
        color_scheme:
          type: string
          description: Emulated color scheme, e.g. "light" or "dark".
        timezone:
          type: string
        disable_twemoji:
          type: boolean
        proxy_id:
          type: string
    CreateImageBatchRequest:
      type: object
      required:
        - variations
      properties:
        default_options:
          $ref: '#/components/schemas/CreateImageRequest'
        variations:
          type: array
          maxItems: 25
          items:
            $ref: '#/components/schemas/CreateImageRequest'
    CreateTemplatedImageRequest:
      type: object
      required:
        - template_values
      properties:
        template_values:
          type: object
          additionalProperties: true
          description: Key/value substitutions for the template's named variables.
    CreateTemplateRequest:
      type: object
      required:
        - html
      properties:
        html:
          type: string
          description: The template HTML, including named variables.
        css:
          type: string
        name:
          type: string
        description:
          type: string
    Image:
      type: object
      properties:
        url:
          type: string
          description: Permanent hosted URL of the rendered image.
        viewBox:
          type: string
          description: The view box used to render the image.
    ImageList:
      type: object
      properties:
        images:
          type: array
          items:
            $ref: '#/components/schemas/Image'
        page_token:
          type: string
          description: Token to retrieve the next page of results.
    Template:
      type: object
      properties:
        template_id:
          type: string
        template_version:
          type: string
        name:
          type: string
        description:
          type: string
    Usage:
      type: object
      properties:
        hourly:
          type: integer
        daily:
          type: integer
        monthly:
          type: integer
        billing_period_total:
          type: integer