Creating a custom deck is perfect for use cases where you want to create a presentation with a variable number of slides (depending on the prompt). If you have a repeated deck creation use case, where you want the same set slides but with content tailored to the prompt, you should create a deck from a template.
Deck Generation Quickstart. If you want to see the minimal steps to generate slides: Quickstart
Configure Custom Branding. If you want to configure your own branding via FlashDocs templates and FlashDocs libraries: Configure
Before we get into all of the cool features and parameters FlashDocs provides for deck generation, we should given a brief overview of how slides are created

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Overview of Custom Deck Generation Process

1

Slide Source: The request does not specify a source_document_id, so the system fetches any (Google Slides / PPTX) library document that is in your organization.

2

Slide Count: The request does not specify a number of slides (number_slides), so the system estimates an appropriate number of slides based on the prompt.

3

Outline Generation: The request does not specify an outline, so the system creates an outline (content & slide layout description for each slide) based on the slide count and prompt.

4

Slide Selection: The request does not include an outline parameter with the slide_id key, so the system selects the most relevant slide from the slide source (library document in step 1) given the outline layout description for each slide.

5

Generation: For each selected slide, the system uses the prompt + outline + placeholders in the slide to generate content for each of the selected slides.

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Specify a FlashDocs Slide Library

You can view and manage all of your FlashDocs Libraries and Templates at dash.flashdocs.ai
If you have multiple libraries (ex: dark vs. light theme or Google Slides vs. PPTX or external facing vs. internal facing branding), you may want to specify which source slides to generate your deck from. The first step is seeing which library FlashDocs documents you have available. You can use the API to programmatically view your slides (API to list documents), but in this demo, we will use the dashboard: For this organiation, we can see that there is only 1 library document - the document in the first row. You can always delete, create, or edit FlashDocs documents in the dashboard.
To specify a library document to use in a deck generation request, we need to identify the id of the document.
If you click on any FlashDocs base presentation, you can find the document id by viewing the URL. Note that this document is a library type (says library under the presentation name). If the URL for this page is https://dash.flashdocs.ai/document/abc0d0d0-abcd-4141-abc0-abc010101#Slides, then the id of the document is the portion between document and #Slides: abc0d0d0-abcd-4141-abc0-abc010101. Now that we have the id of the library FlashDocs document we want our custom deck to come from, we can include the source_document_id in the generate deck request: 
curl --request POST \
  --url https://api.flashdocs.ai/v3/generate/deck \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
  "prompt": "Make a slide deck explaining why programmatic slide deck creation is a game changer for my business. Describe all of the new features we can add.",
  "source_document_id": "abc0d0d0-abcd-4141-abc0-abc010101"
}'

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How does this affect the generation of the deck?

Specifying the source_document_id affects step 4 in the deck generation process. When the system identifies the most relevant slide layout for each slide in the outline, it chooses a slide layout from the set of slides in the source_document_id.

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Number of Slides

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Description

The number_slides parameter allows you to specify the exact number of slides you want in the generated presentation. If omitted, the system automatically estimates an appropriate slide count based on the prompt. (Note: This parameter should not be used if the source_document_id points to a template document.) 
curl --request POST \
  --url https://api.flashdocs.ai/v3/generate/deck \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
    "prompt": "Explain the impact of renewable energy on modern businesses.",
    "number_slides": 5,
    "source_document_id": "abc0d0d0-abcd-4141-abc0-abc010101"
  }'

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Generation Process Impact

The number_slides parameter directly affects Step 2: Slide Count. When provided, the system bypasses its automatic estimation and uses the specified number to generate the presentation. Under the hood, this parameter informs the algorithm to tailor the outline and distribute content evenly across the defined number of slides.

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Outline

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Description

The outline parameter lets you supply a custom array of instructions that define both the content and layout for each slide. This is particularly useful for custom decks where you want to control slide-by-slide details. If an outline is not provided, the system automatically generates one based on the prompt. Instead of layout_instruction, you can also directly provide slide_id, which is the id of the slide in a FlashDocs document. You can view slide IDs in this request: https://docs.flashdocs.com/api-reference/flashdocs-documents/get-document-full-data, with 
curl --request POST \
  --url https://api.flashdocs.ai/v3/generate/deck \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
    "prompt": "Discuss emerging technology trends in 2025.",
    "outline": [
      {
        "layout_instruction": "Title slide with bold graphics",
        "content_instruction": "Introduce the topic and set the stage."
      },
      {
        "layout_instruction": "Slide with 3 sections",
        "content_instruction": "Highlight the top 3 emerging trends."
      }
    ],
    "source_document_id": "abc0d0d0-abcd-4141-abc0-abc010101"
  }'

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Generation Process Impact

The outline parameter influences Step 3: Outline Generation. When provided, it overrides the system’s default outline generation process, guiding the creation of slide layouts and content structure. Internally, the provided instructions are mapped to the corresponding slide placeholders to ensure that each slide adheres to your specific design and content requirements.

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Audience Domain

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Description

The audience_domain parameter is used to specify the domain or website of the target audience. This is particularly useful for populating image placeholders with the appropriate company logos (using the audience-company-logo category) when the deck is designed for an external audience. If not provided, the system attempts to predict a suitable domain. 
curl --request POST \
  --url https://api.flashdocs.ai/v3/generate/deck \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
    "prompt": "Showcase our innovative product suite to potential clients.",
    "audience_domain": "apple.com",
    "source_document_id": "abc0d0d0-abcd-4141-abc0-abc010101"
  }'

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Generation Process Impact

The audience_domain parameter affects the Generation step (Step 5). When set, the system leverages this information to look up and assign the correct branding assets (such as company logos) to image placeholders. Under the hood, this triggers a lookup for image assets corresponding to the specified domain, ensuring that the visual elements align with the intended audience’s identity.

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Presentation Name

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Description

The presentation_name parameter allows you to define a custom filename for the generated presentation deck. If this parameter is omitted, the system will automatically generate a name based on the provided prompt. 
curl --request POST \
  --url https://api.flashdocs.ai/v3/generate/deck \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
    "prompt": "Create a presentation on climate change and sustainability initiatives.",
    "presentation_name": "Climate Change Initiatives 2025",
    "source_document_id": "abc0d0d0-abcd-4141-abc0-abc010101"
  }'

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Generation Process Impact

The presentation_name parameter primarily influences the final output of the deck generation process. While it does not affect the content or slide structure, it determines the filename and title of the resulting deck. Internally, once all slides have been generated, this parameter is applied to name the file, making it easier to identify and share.

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Google Slides Add Editors

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Description

The google_document_editors parameter is an array of email addresses that will receive edit access to the generated Google Slides presentation. This feature supports collaborative editing and is only applicable to presentations generated in Google Slides format; it is ignored for PowerPoint presentations. 
curl --request POST \
  --url https://api.flashdocs.ai/v3/generate/deck \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
    "prompt": "Prepare a collaborative project update deck.",
    "google_document_editors": ["alice@example.com", "bob@example.com"],
    "source_document_id": "abc0d0d0-abcd-4141-abc0-abc010101"
  }'

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Generation Process Impact

The google_document_editors parameter is applied once the deck has been fully generated. It automates the sharing process by interfacing with the Google Slides API to grant the specified email addresses edit permissions on the generated presentation. This ensures seamless collaboration, allowing team members to make further edits directly in the document.