PDF form filling API

Integrate our PDF form filler API to import and fill PDF forms in your application or workflow.

Dynamic, data-driven filling

Import data into fillable fields across any PDF form using a simple JSON structure.

Automate with Zapier

Automatically fill new PDF forms in Google Drive using our Zapier integration. Just upload a form and your data, and Nutrient will handle the rest.

Seamless integration

Connect to your apps or workflows to generate prefilled forms for contracts, registration, compliance, and more.

Used by Lufthansa, Disney, Autodesk, UBS, Dropbox, IBM
Lufthansa
Disney
Autodesk
UBS
Dropbox
IBM

Try it out

This example will import Instant JSON to fill forms in a PDF.


Try it out in three steps

  1. Add forms.pdf and form-filling.json to your project folder.
  2. Run the code from the same folder.
  3. Open result.pdf to see the output.
curl -X POST https://api.nutrient.io/build \
-H "Authorization: Bearer your_api_key_here" \
-o result.pdf \
--fail \
-F document=@form.pdf \
-F form_filling.json=@form_filling.json \
-F instructions='{
"parts": [
{
"file": "document"
}
],
"actions": [
{
"type": "applyInstantJson",
"file": "form_filling.json"
}
]
}'

Start now

Create an account to access your API key and start with 50 free credits per month

Start building with DWS Processor API in minutes — no payment information required.

Already have an account? Sign in →

Instant JSON

The Instant JSON format is the native format of the Nutrient API for representing form fields and annotations. Use this format to programmatically populate, update, and manage form fields in your documents.

Instant JSON annotation format

Security is our top priority

No document storage

No input or resulting documents are stored on our infrastructure. All files are deleted as soon as a request finishes. Alternatively, check out our self-hosted product.

HTTPS encryption

All communication between your application and Nutrient is done via HTTPS to ensure your data is encrypted when it’s sent to us.

Safe payment processing

All payments are handled by Paddle. Nutrient DWS Processor API never has direct access to any of your payment data.

PDF form filling API questions

What is a PDF form filling API?

A PDF form filling API populates fillable form fields in PDF documents over a REST endpoint. Nutrient’s DWS Processor API imports your data as Instant JSON or XFDF and returns the filled PDF, so you can automate prefilled contracts, registration, and compliance forms.

What’s the difference between Instant JSON and XFDF?

Instant JSON is Nutrient’s native format for representing form field values and annotations; XFDF is the XML-based standard for exchanging form data between PDF tools. The API accepts both — see the Instant JSON import API and the XFDF import API.

Can I create new form fields, not just fill existing ones?

Yes. Use the PDF form creator API to add new form fields to a document. Then fill them with this API in the same workflow.

Which programming languages are supported?

You can call the API from any language that makes HTTP requests. Nutrient provides examples for JavaScript, Python, Java, C# (.NET), and PHP, plus curl, a Postman collection, and raw HTTP.

Is the PDF form filling API SOC 2 compliant?

Yes. The API is backed by Nutrient’s SOC 2 Type 2-audited infrastructure — built for use in business-critical and regulated workflows.

Is there a free tier for the PDF form filling API?

Yes. Sign up to receive free processing credits and test form filling before choosing a plan. See the Processor API pricing page for credit details.

Ready to try it?

Create an account to get your DWS Processor API key and start making API calls.