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JSON API to PPTX for proposals: 6 document generation tools

For proposals, we list 6 tools that turn JSON sent to an API into a PowerPoint deck. The lowest paid starting price is $19 a month, from SourceToDocs. The first three in our order are Conga Composer, Formstack Documents and SourceToDocs.

Tools
6
With USD price
4, from $19
Free tier
3
Direct / via Zapier
5 / 1
Checked
20 Oct 2026
  1. 01
    Conga Composer Editor's pick conga.com

    Enterprise Salesforce document generation.

    Outputs PDF, DOCX, XLSX, PPTX, HTML, email Template Word Also reads Salesforce G2 4.4 (849)
    Not published
  2. 02
    Formstack Documents Editor's pick formstack.com

    Formerly WebMerge. Only in Suite plan, $250/mo paid annually, 250 deliveries/mo.

    Outputs PDF, DOCX, PPTX, e-sign documents Template Word, PDF form, Visual builder Also reads Salesforce, HubSpot, Airtable, built-in forms +2 G2 4.5 (148)
    $250 / mo
  3. 03
    SourceToDocs sourcetodocs.com

    Data to Google Slides and Docs.

    Outputs Google Slides, Google Docs, PDF, PPTX, DOCX, HTML Template Google Docs Also reads Airtable, Google Sheets, CSV
    $19 / mo, cheapest here
  4. 04
    Templafy templafy.com

    AI document agents in Microsoft Office.

    Outputs PPTX, DOCX, PDF Template Word Also reads Salesforce
    $40 / mo
  5. 05
    Gamma gamma.app

    AI presentations. Exports PPTX, PDF, Google Slides on Free.

    Outputs PPTX, PDF, Google Slides Template Visual builder Also reads HubSpot
    Not published free tier
  6. 06
    Docupilot Editor's pick via Zapier docupilot.com

    Starter $29/mo, 100 docs.

    Outputs PDF, DOCX, PPTX, XLSX, e-sign documents Template Word, Visual builder Also reads Airtable, Zapier/Make/n8n, built-in forms
    $29 / mo

What differs for JSON API

For proposals delivered as PPTX, templates are built in Word (4), a visual builder (3) and Google Docs (1). Among them, 1 needs Zapier, Make or n8n to read JSON sent to an API, so it sits after the tools with a direct connection. Of these, 3 have a free tier.

Besides PPTX, these tools for proposals also write PDF (6), DOCX (5) and Google Slides (2). Your own code decides when to call the API, so a document can be built on any event. Published starting prices run from $19 to $250 a month, the top end from Formstack Documents. Prices were checked on 20 Oct 2026.

Nearby pages

Broader list: JSON API to PPTX (11 tools).

Related lists: JSON API to PPTX for reports (9 tools), JSON API to PPTX for invoices (7), JSON API to PPTX for contracts (5), JSON API to PDF for proposals (11), JSON API to DOCX for proposals (7), JSON API to e-sign documents for proposals (6).

How to generate PDFs from a JSON API: a step-by-step guide, updated 21 Oct 2026.

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