Fill PDF forms with JSON — at scale, on every plan

Reuse legally-approved PDF templates. Fill thousands of contracts, applications, and government forms with one API call.

Hosted in Frankfurt & Paris
GDPR-compliant

AcroForm + XFAPAdES signaturesField validation

Why fill PDF forms via API?

Compliance with existing templates

Use the exact PDFs your legal team approved. No re-creating forms in HTML, no risk of layout drift between source and output.

Scale without manual entry

Fill thousands of W-9s, NDAs, lease agreements, or government forms per minute — the same API call regardless of volume.

Audit-ready output

Optional flatten + sign step turns a fillable form into an immutable, tamper-evident archived PDF.

How PDF form filling works

1. Upload the source form once

Drop the source PDF into your workspace via dashboard or API. We extract field names and store the template.

2. POST JSON data

Send a JSON object keyed by field name (or position-based for unnamed fields) to /v1/render with source: 'form'.

3. Receive filled PDF

Get the filled PDF back — optionally flattened (read-only) or signed (PAdES tamper-evidence).

What is the pdf.xhub PDF Form Filling API?

A programmatic interface for the long tail of paperwork that still ships as fillable PDFs: government forms, legal contracts, insurance applications. We support both AcroForm and the older XFA spec.

Try it in your stack

Same endpoint. Copy as cURL, call from any language.

Fill existing PDF forms with JSON. Ideal for fixed-template workflows: contracts, government forms, insurance applications.

curl -X POST https://api.pdf.xhub.io/v1/render \
  -H "Authorization: Bearer $PDFXHUB_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "source": "form",
    "formId": "form_W9_2026",
    "data": {
      "name": "Acme GmbH",
      "taxId": "DE123456789"
    }
  }' --output filled.pdf

curl -X POST https://api.pdf.xhub.io/v1/render \
  -H "Authorization: Bearer $PDFXHUB_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "source": "form",
    "formId": "form_W9_2026",
    "data": {
      "name": "Acme GmbH",
      "taxId": "DE123456789"
    }
  }' --output filled.pdf

Features at a glance

Form support

AcroForm + XFA form spec support
Field-name + index-based filling
Conditional fields (show/hide via JSON)
Checkbox, radio, dropdown, text, signature fields
Image insertion for signature fields
Multi-page form merging

Output & Compliance

Flatten step (convert to read-only)
PAdES digital signatures
Validation errors returned with clear messages
GDPR-compliant by default — DPA + SCCs included

Platform

EU-only render workers (Frankfurt + Paris)
Form template versioning + audit log
Webhook on async batch completion
Per-field validation with clear JSON errors
OpenAPI 3.1 with full form-field schemas
Rate limit scales linearly with tier

Other ways to render

Same API, different inputs.

Automate your form-filling pipeline

25 fills/month free forever. Reuse your legal-approved templates.

Create free account Read the docs