Onboarding pack generators for JSON API

If you need an onboarding pack built from JSON sent to an API, 7 tools here can make one. The first three in our order are Formstack Documents, Anvil and DocSpring. Of these, 5 have a free tier.

Tools: 7
With USD price: 7, from $20
Free tier: 5
Direct / via Zapier: 5 / 2
Checked: 20 Oct 2026

01

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
02

Anvil Editor's pick useanvil.com

PDF fill, generate, e-sign API.

Outputs PDF, e-sign documents Template PDF form, HTML

$99 / mo
03

DocSpring docspring.com

PDF form filling and HTML PDFs.

Outputs PDF Template PDF form, HTML

$49 / mo
04

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
05

Crove via Zapier crove.app

Individual $33/mo billed $390/yr.

Outputs PDF, DOCX, e-sign documents Template Word, Visual builder Also reads built-in forms, Zapier/Make/n8n

$33 / mo
06

DocuSeal docuseal.com

Open-source e-sign and PDF form builder.

Outputs PDF, e-sign documents Template PDF form Also reads built-in forms

$20 / mo, cheapest here
07

Dropbox Sign API sign.dropbox.com

Adjacent e-sign API with templates.

Outputs e-sign documents, PDF Template PDF form

$75 / mo

What differs for JSON API

For onboarding packs built from JSON sent to an API, the lowest paid starting price is $20 a month, from DocuSeal. Published starting prices run from $20 to $250 a month, the top end from Formstack Documents.

These tools for onboarding packs most often write PDF (7), e-sign documents (6) and DOCX (3). Among them, 2 need Zapier, Make or n8n to read JSON sent to an API, so they sit after the tools with a direct connection. Your own code decides when to call the API, so a document can be built on any event. Prices were checked on 20 Oct 2026.

Nearby pages

Broader list: Document generation APIs (64 tools).

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

All tools, with filters for source, output, use case and price.

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